TRUB2 is a mitochondrial pseudouridine synthase belonging to the TruB family that catalyzes the site-specific isomerization of uridine to pseudouridine (Psi) in mitochondrial RNAs. In mammals, TRUB2 functions as a tRNA pseudouridine-55 synthase, converting U55 in the TPC loop of select mitochondrial tRNAs to Psi55, a modification that stabilizes tRNA tertiary structure through base-pairing with the D-loop. TRUB2 localizes to mitochondrial RNA granules, where it participates in a pseudouridine synthase module together with RPUSD3, RPUSD4, FASTKD2, and other RNA-binding proteins. Beyond tRNA modification, TRUB2 contributes to pseudouridylation of specific mitochondrial mRNAs (MT-CO1, MT-CO3). TRUB2-mediated RNA modifications are essential for mitochondrial translation and oxidative phosphorylation complex assembly; depletion of TRUB2 in human cells reduces synthesis of mtDNA-encoded polypeptides and impairs ATP synthase assembly. The Columba livia ortholog (142 amino acids) contains the conserved pseudouridine synthase II N-terminal domain (PF01509) and is classified in the Trub2-specific InterPro family (IPR039048), supporting functional equivalence with mammalian TRUB2.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
|
GO:0001522
pseudouridine synthesis
|
IEA
GO_REF:0000002 |
MODIFY |
Summary: Correct biological process. TRUB2 catalyzes pseudouridine formation in mitochondrial tRNAs and mRNAs; pseudouridine synthesis is its core biological process. However, a more specific term exists: GO:0070902 (mitochondrial tRNA pseudouridine synthesis) better captures the primary process for this mitochondrial enzyme.
Reason: The general term is accurate but too broad. TRUB2 is specifically a mitochondrial pseudouridine synthase; GO:0070902 (mitochondrial tRNA pseudouridine synthesis) is the appropriate specific process based on mammalian ortholog evidence.
Proposed replacements:
mitochondrial tRNA pseudouridine synthesis
|
|
GO:0003723
RNA binding
|
IEA
GO_REF:0000002 |
KEEP AS NON CORE |
Summary: Correct but generic. As a pseudouridine synthase that acts directly on RNA substrates (mitochondrial tRNAs and mRNAs), TRUB2 necessarily binds RNA. The TruB family uses a substrate-flipping mechanism that requires direct RNA contact. However, RNA binding is ancillary to the catalytic function and does not provide informative annotation beyond what the pseudouridine synthase activity already implies.
Reason: RNA binding is an inherent mechanistic property of this RNA-modifying enzyme, not a distinct core function. It is accurate but uninformative beyond the primary catalytic annotation.
|
|
GO:0006396
RNA processing
|
IEA
GO_REF:0000002 |
MARK AS OVER ANNOTATED |
Summary: Pseudouridylation is a post-transcriptional RNA modification, which falls under the umbrella of RNA processing. However, the more precise term GO:0009451 (RNA modification) is already annotated and better captures the nature of TRUB2's activity. RNA processing is overly broad and could imply splicing, cleavage, or other processing events that TRUB2 does not perform.
Reason: Too broad. GO:0009451 (RNA modification), which is already annotated, is the correct parent-level process term. RNA processing implies a wider range of activities than what TRUB2 performs.
|
|
GO:0009451
RNA modification
|
IEA
GO_REF:0000002 |
KEEP AS NON CORE |
Summary: Correct general biological process. TRUB2 performs RNA modification (specifically pseudouridylation). This is a valid parent term of the more specific pseudouridine synthesis process. Since a more specific term (pseudouridine synthesis / mitochondrial tRNA pseudouridine synthesis) is available and preferred, this annotation is redundant but not incorrect.
Reason: Accurate parent-level process term, but redundant given the more specific pseudouridine synthesis annotation. Kept as non-core since it adds no specificity beyond the more informative annotations.
|
|
GO:0009982
pseudouridine synthase activity
|
IEA
GO_REF:0000002 |
MODIFY |
Summary: Correct molecular function. TRUB2 is a bona fide pseudouridine synthase that catalyzes uridine-to-pseudouridine isomerization. However, a more specific term exists: GO:0160148 (tRNA pseudouridine(55) synthase activity) precisely describes the established enzymatic specificity of TRUB2 for the Psi55 position in tRNAs. GO:0106029 (tRNA pseudouridine synthase activity) would also be appropriate as an intermediate-specificity annotation.
Reason: The general pseudouridine synthase activity term is accurate but too broad. Based on mammalian ortholog evidence, TRUB2 specifically catalyzes tRNA pseudouridine-55 formation; GO:0160148 (tRNA pseudouridine(55) synthase activity) captures this specificity. The ProtNLM2 prediction review also noted that GO:0106029 (tRNA pseudouridine synthase activity) is a more specific correct term.
Proposed replacements:
tRNA pseudouridine(55) synthase activity
|
The research report should be a detailed narrative explaining the function, biological processes, and localization of the gene product. Citations should be given for all claims.
You should prioritize authoritative reviews and primary scientific literature when conducting research. You can supplement
this with annotations you find in gene/protein databases, but these can be outdated or inaccurate.
We are specifically interested in the primary function of the gene - for enzymes, what reaction is catalyzed, and what is the substrate specificity? For transporters, what is the substrate? For structural proteins or adapters, what is the broader structural role? For signaling molecules, what is the role in the pathway.
We are interested in where in or outside the cell the gene product carries out its function.
We are also interested in the signaling or biochemical pathways in which the gene functions. We are less interested in broad pleiotropic effects, except where these elucidate the precise role.
Include evidence where possible. We are interested in both experimental evidence as well as inference from structure, evolution, or bioinformatic analysis. Precise studies should be prioritized over high-throughput, where available.
The gene TRUB2 (UniProt A0A2I0M3K7) in Columba livia (Rock dove) encodes a protein annotated as "TruB pseudouridine (Ψ) synthase family member 2" that belongs to the pseudouridine synthase TruB family (zucchini2003thehumantrub pages 1-2). While no direct experimental studies have been published on the Rock dove ortholog, the gene's function can be reliably inferred from extensive research on mammalian TRUB2 orthologs, which are highly conserved members of the TruB/Pus4 pseudouridine synthase family (zucchini2003thehumantrub pages 1-2, lin2025mechanisticinsightinto pages 9-10).
TRUB2 functions as a pseudouridine synthase enzyme that catalyzes the site-specific isomerization of uridine (U) to pseudouridine (Ψ) in structured RNA molecules (mukhopadhyay2021mammaliannucleartrub1 pages 1-2, zucchini2003thehumantrub pages 1-2). The reaction involves converting the N-glycosidic bond between uracil N1 and ribose C1 into a C-glycosidic bond between uracil C5 and ribose C1, creating the unusual C-C linkage characteristic of pseudouridine (zucchini2003thehumantrub pages 1-2, lin2025mechanisticinsightinto pages 9-10). This post-transcriptional modification is one of the most abundant RNA modifications and plays critical roles in RNA structure, stability, and function.
The TruB family, to which TRUB2 belongs, contains conserved catalytic motifs including motif I (with conserved proline and lysine residues contributing to protein structure) and motif II (containing a highly conserved aspartic acid residue essential for catalytic activity) (zucchini2003thehumantrub pages 1-2, lin2025mechanisticinsightinto pages 9-10). The catalytic mechanism is evolutionarily conserved across TruB family members from bacteria to mammals, suggesting that the Rock dove TRUB2 employs the same fundamental catalytic strategy (lin2025mechanisticinsightinto pages 9-10).
Based on mammalian studies, TRUB2 is specifically localized to mitochondria, where it functions within the mitochondrial matrix and is associated with mitochondrial RNA granules (mukhopadhyay2021mammaliannucleartrub1 pages 1-2, antonicka2017apseudouridinesynthase pages 1-2). This localization is distinct from its paralog TRUB1, which is predominantly nuclear, and from PUS10, which is primarily cytoplasmic (mukhopadhyay2021mammaliannucleartrub1 pages 1-2, mukhopadhyay2021mammaliannucleartrub1 pages 2-3). The compartmentalization of these related pseudouridine synthases suggests specialized, non-redundant functions in different cellular locations.
Mitochondrial RNA granules are non-membrane-delimited structures that serve as platforms for post-transcriptional RNA modification, processing, and ribosome assembly (antonicka2017apseudouridinesynthase pages 1-2). TRUB2 has been identified as part of a pseudouridine synthase module in these granules, interacting with other RNA-binding proteins including RPUSD3, RPUSD4, FASTKD2, WBSCR16, NGRN, and METTL15 (antonicka2017apseudouridinesynthase pages 1-2, antonicka2017apseudouridinesynthase pages 2-3). This protein module coordinates the modification and maturation of mitochondrial RNAs.
TRUB2 exhibits dual substrate specificity, acting on both mitochondrial transfer RNAs (tRNAs) and mitochondrial messenger RNAs (mRNAs):
TRUB2 functions as a mitochondrial tRNA Ψ55 synthase, catalyzing the formation of pseudouridine at position 55 in the TΨC loop of select mitochondrial tRNAs (mukhopadhyay2021mammaliannucleartrub1 pages 1-2, mukhopadhyay2021mammaliannucleartrub1 pages 2-3). The Ψ55 modification is functionally important because it participates in a tertiary base pair with the adenosine or guanosine at position 18 in the D-loop, stabilizing the characteristic L-shaped tRNA structure (jia2022humantrub1is pages 1-2).
Substrate recognition by TRUB2 has specific structural requirements that distinguish it from TRUB1. Biochemical studies using recombinant proteins demonstrated that TRUB2 requires the presence of both U54 and A58 forming a reverse Hoogsteen base pair for efficient Ψ55 synthesis activity (mukhopadhyay2021mammaliannucleartrub1 pages 2-3). When either U54 or A58 is mutated, TRUB2 loses its pseudouridylation activity, whereas TRUB1 can still modify these mutant substrates (mukhopadhyay2021mammaliannucleartrub1 pages 2-3). Additionally, the presence of 1-methyladenosine (m1A58) at position 58 enhances TRUB2 activity, demonstrating cross-talk between different RNA modification systems (mukhopadhyay2021mammaliannucleartrub1 pages 2-3).
TRUB2, in conjunction with RPUSD3, also catalyzes pseudouridylation of specific sites in mitochondrial mRNAs (antonicka2017apseudouridinesynthase pages 2-3, antonicka2017apseudouridinesynthase pages 3-7, jedynakslyvka2021humanmitochondrialrna pages 9-11). Pseudouridine-sequencing (Ψ-Seq) analysis following TRUB2 depletion identified modifications at:
- MT-CO1 (COXI) mRNA position 391 (Ψ391)
- MT-CO3 (COXIII) mRNA positions 698-700 (Ψ698-700)
Evidence suggests that RPUSD3 is likely the primary enzyme responsible for these mRNA modifications, with TRUB2 playing a secondary or supporting role (antonicka2017apseudouridinesynthase pages 7-8, antonicka2017apseudouridinesynthase pages 3-7, jedynakslyvka2021humanmitochondrialrna pages 9-11). The modified sites are located in loops or stems adjacent to loops, making them structurally accessible for enzyme binding (antonicka2017apseudouridinesynthase pages 3-7).
A recent comprehensive 2025 study mapping human tRNA pseudouridine sites found that TRUB2 "does not exhibit noticeable enzymatic activity" in their HCT116 cell-based assay system (xu2025acomprehensivetrna pages 2-3). This contrasts with earlier studies showing clear TRUB2 activity in mitochondrial extracts and in vitro systems (mukhopadhyay2021mammaliannucleartrub1 pages 1-2, mukhopadhyay2021mammaliannucleartrub1 pages 2-3, antonicka2017apseudouridinesynthase pages 1-2). This discrepancy suggests that TRUB2 activity may be:
- Context-dependent (requiring specific cellular conditions or stress signals)
- Cell-type-specific
- Dependent on cofactors or post-translational modifications not present in all experimental systems
- Mitochondrial compartment-specific (activity only evident in isolated mitochondrial fractions)
This uncertainty does not negate the earlier mitochondrial evidence but highlights that TRUB2's native substrate range and regulation may be more complex than initially appreciated.
TRUB2 plays essential roles in multiple interconnected mitochondrial processes:
TRUB2 is critical for mitochondrial translation. siRNA-mediated depletion of TRUB2 in human cells resulted in decreased synthesis of mitochondrial DNA-encoded polypeptides, with particularly severe effects on the synthesis of ATP6 and ATP8 proteins encoded by a bicistronic transcript (antonicka2017apseudouridinesynthase pages 2-3, antonicka2017apseudouridinesynthase pages 3-7). Importantly, these translation defects occurred without major changes in mitochondrial mRNA abundance, indicating that TRUB2-mediated RNA modifications directly influence translational efficiency rather than transcript stability (antonicka2017apseudouridinesynthase pages 2-3).
TRUB2 depletion causes combined OXPHOS assembly defects, particularly affecting complex V (ATP synthase) assembly due to the reduced synthesis of ATP6 and ATP8 subunits (antonicka2017apseudouridinesynthase pages 2-3, antonicka2017apseudouridinesynthase pages 3-7). Blue native PAGE analysis revealed decreased levels of assembled OXPHOS complexes, demonstrating that TRUB2-mediated RNA modifications are essential for maintaining the bioenergetic capacity of mitochondria.
TRUB2 functions as part of a coordinated pseudouridine synthase module involved in mitochondrial ribosome assembly (antonicka2017apseudouridinesynthase pages 1-2, antonicka2017apseudouridinesynthase pages 2-3). Depletion of TRUB2 led to decreased levels of MRPL11, a protein of the mitochondrial large ribosomal subunit (mt-LSU), and affected the assembly of the mitochondrial ribosome (antonicka2017apseudouridinesynthase pages 2-3). This suggests that proper pseudouridylation of mitochondrial RNAs by TRUB2 is required for efficient ribosome biogenesis.
TRUB2 has been identified as a core essential gene in CRISPR/Cas9 screens across multiple human cell lines (antonicka2017apseudouridinesynthase pages 1-2). This essential nature reflects the critical dependence of cellular function on mitochondrial translation and energy production. The loss of TRUB2 function would be expected to compromise cellular ATP production and survival, particularly in cells with high metabolic demands.
While direct structural data for TRUB2 specifically are limited, the enzyme can be understood through the well-characterized structural features of the TruB family (lin2025mechanisticinsightinto pages 9-10). TruB family enzymes exhibit:
The requirement for the U54·A58 reverse Hoogsteen pair indicates that TRUB2 recognizes specific three-dimensional RNA structures rather than simple linear sequence motifs (mukhopadhyay2021mammaliannucleartrub1 pages 2-3).
The human TruB family includes at least three members: DKC1 (which primarily modifies ribosomal RNA), TRUB1 (primarily nuclear and cytoplasmic tRNA modifier), and TRUB2 (mitochondrial) (zucchini2003thehumantrub pages 1-2). Among these, TRUB1 and TRUB2 likely arose through gene duplication and subsequently evolved distinct subcellular localizations and substrate specificities. The bacterial TruB enzyme, which modifies cytoplasmic tRNAs, is orthologous to yeast Pus4 and represents the ancestral form of this enzyme family (zucchini2003thehumantrub pages 1-2, jia2022humantrub1is pages 1-2).
The evolutionary conservation of the TruB domain from bacteria through mammals suggests that the Rock dove TRUB2 will share the same fundamental catalytic mechanism and likely similar substrate recognition properties as mammalian TRUB2, though the precise complement of tRNA substrates may vary between species.
| Feature | Summary for TRUB2 ortholog inference | Evidence / details | Key study (date) | Citation |
|---|---|---|---|---|
| Target identity relevant to rock dove protein | The UniProt-described Columba livia protein A0A2I0M3K7 is annotated as a TruB pseudouridine synthase family member (gene symbol TRUB2), so the most appropriate functional inference is from mammalian TRUB2 orthologs rather than unrelated genes with similar names. | Human TRUB2 was recognized as a member of the human TruB family of pseudouridine synthases; TRUB family proteins are putative RNA pseudouridine synthases. | Zucchini et al., 2003-06-01 | (zucchini2003thehumantrub pages 1-2) |
| Protein family / conserved domains | TRUB2 belongs to the TruB/Pus4 pseudouridine synthase family, whose members catalyze site-specific uridine-to-pseudouridine isomerization in structured RNAs. Conserved motifs include motif I and motif II, with motif II carrying the catalytic Asp residue. | Human TruB family papers identify TRUB2 as a TruB homolog; mechanistic reviews describe conserved catalytic architecture and aspartate-centered catalysis across PUS enzymes. | Zucchini et al., 2003-06-01; Lin et al., 2025 | (zucchini2003thehumantrub pages 1-2, lin2025mechanisticinsightinto pages 9-10) |
| Core enzymatic reaction | TRUB2 is inferred to catalyze isomerization of uridine (U) to pseudouridine (Ψ) in RNA, producing a C–C glycosidic linkage between uracil C5 and ribose C1 instead of the usual N1–C1 bond. | This is the canonical reaction of TruB-family pseudouridine synthases; the family uses a conserved catalytic Asp. | Zucchini et al., 2003-06-01; Lin et al., 2025 | (zucchini2003thehumantrub pages 1-2, lin2025mechanisticinsightinto pages 9-10) |
| Subcellular localization | In mammals, TRUB2 is primarily mitochondrial, with activity detected mainly in mitochondrial extracts rather than nuclear or cytoplasmic fractions. | A compartmentalization study assigned TRUB2 to mitochondria; BioID/immunofluorescence studies placed TRUB2 in mitochondrial RNA granule-associated networks. | Mukhopadhyay et al., 2021-10-00; Antonicka et al., 2017-01-00 | (mukhopadhyay2021mammaliannucleartrub1 pages 1-2, antonicka2017apseudouridinesynthase pages 1-2) |
| Intra-mitochondrial site of action | TRUB2 is associated with mitochondrial RNA granules, sites of post-transcriptional mtRNA processing and ribosome assembly. | TRUB2 was found in a mitochondrial pseudouridine synthase module together with RPUSD3/RPUSD4 and other RNA granule proteins. | Antonicka et al., 2017-01-00 | (antonicka2017apseudouridinesynthase pages 1-2, antonicka2017apseudouridinesynthase pages 2-3) |
| tRNA substrate class | TRUB2 can act as a tRNA Ψ55 synthase in mammals, especially in the mitochondrial compartment. | Recombinant human TRUB2 produced Ψ55 in tRNA substrates in vitro; mitochondrial extracts depended on TRUB2 for much of the Ψ55 synthase activity. | Mukhopadhyay et al., 2021-10-00 | (mukhopadhyay2021mammaliannucleartrub1 pages 1-2, mukhopadhyay2021mammaliannucleartrub1 pages 2-3) |
| tRNA target position | The best-supported tRNA target position is U55 in the TΨC loop, converted to Ψ55. | Mammalian study explicitly showed that TRUB1, TRUB2, and PUS10 all have Ψ55 synthase activities, partitioned by compartment and substrate constraints. | Mukhopadhyay et al., 2021-10-00 | (mukhopadhyay2021mammaliannucleartrub1 pages 1-2, mukhopadhyay2021mammaliannucleartrub1 pages 2-3) |
| Candidate mitochondrial tRNA targets | Reviews and mitochondrial-RNA summaries have suggested TRUB2 contributes to Ψ formation in mitochondrial RNAs, but exact mt-tRNA target repertoires remain less firmly resolved than for TRUB1. | Earlier literature suggested mitochondrial TRUB2 could account for some mt-tRNA Ψ55 sites; later work more clearly established TRUB1 for several mt-tRNAs, leaving TRUB2’s exact native tRNA scope somewhat uncertain. | Mukhopadhyay et al., 2021-10-00; Jia et al., 2022-08-26 | (mukhopadhyay2021mammaliannucleartrub1 pages 1-2, jia2022humantrub1is pages 1-2) |
| mRNA substrate class | TRUB2 also has evidence for acting on mitochondrial mRNAs. | Pseudouridine-seq after TRUB2 depletion implicated TRUB2/RPUSD3 in pseudouridylation of COXI and COXIII mitochondrial mRNAs. | Antonicka et al., 2017-01-00 | (antonicka2017apseudouridinesynthase pages 2-3, antonicka2017apseudouridinesynthase pages 3-7) |
| Specific mitochondrial mRNA sites | Candidate TRUB2-linked sites include MT-CO1 position 391 and MT-CO3 positions 698–700 (human mtRNA numbering in review summary). | A 2021 review summarizes RPUSD3/TRUB2-dependent pseudouridylation at CO1 and CO3; the primary study concluded RPUSD3 is likely the major enzyme, with TRUB2 a secondary contributor. | Jedynak-Slyvka et al., 2021-07-30; Antonicka et al., 2017-01-00 | (jedynakslyvka2021humanmitochondrialrna pages 9-11, antonicka2017apseudouridinesynthase pages 7-8, antonicka2017apseudouridinesynthase pages 3-7) |
| Substrate recognition requirements | TRUB2 shows stricter local structural requirements than TRUB1 for Ψ55 formation, notably dependence on a U54·A58 reverse Hoogsteen pair. | Mutational analysis showed TRUB2 and PUS10 lost Ψ55 activity when U54 or A58 pairing constraints were disrupted, whereas TRUB1 was more permissive. | Mukhopadhyay et al., 2021-10-00 | (mukhopadhyay2021mammaliannucleartrub1 pages 2-3) |
| Effect of adjacent modifications | m1A58 can enhance TRUB2-mediated Ψ55 formation. | In vitro assays found increased TRUB2 Ψ55 production in the presence of m1A58. | Mukhopadhyay et al., 2021-10-00 | (mukhopadhyay2021mammaliannucleartrub1 pages 2-3) |
| Likely catalytic mechanism | Like other TruB-family enzymes, TRUB2 likely binds a structured RNA loop/hairpin, flips the target uridine into the active site, and catalyzes rearrangement through the conserved Asp-centered active site. | Direct TRUB2 structural data are limited, but family-level structural/mechanistic work supports this inference. | Lin et al., 2025 | (lin2025mechanisticinsightinto pages 9-10) |
| Biological process: mitochondrial translation | TRUB2 supports mitochondrial protein synthesis. Its depletion reduces synthesis of mtDNA-encoded proteins. | siRNA depletion produced mitochondrial translation defects without major mt-mRNA abundance changes. | Antonicka et al., 2017-01-00 | (antonicka2017apseudouridinesynthase pages 2-3, antonicka2017apseudouridinesynthase pages 3-7) |
| Biological process: OXPHOS biogenesis | TRUB2 is required for efficient oxidative phosphorylation (OXPHOS) complex assembly, with especially notable effects on ATP6/ATP8 synthesis and downstream respiratory-chain assembly. | TRUB2 depletion reduced ATP6/ATP8 synthesis from the bicistronic transcript and caused combined OXPHOS defects. | Antonicka et al., 2017-01-00 | (antonicka2017apseudouridinesynthase pages 2-3, antonicka2017apseudouridinesynthase pages 3-7) |
| Biological process: mitoribosome / RNA-granule pathway | TRUB2 participates in a broader mitochondrial RNA processing and ribosome biogenesis network. | TRUB2 interacts with FASTKD2, RPUSD3, RPUSD4, WBSCR16, NGRN, and METTL15 in a pseudouridine synthase module linked to RNA granules and mt-LSU assembly. | Antonicka et al., 2017-01-00 | (antonicka2017apseudouridinesynthase pages 1-2, antonicka2017apseudouridinesynthase pages 2-3) |
| Essentiality / cellular importance | TRUB2 has been identified as a core essential gene in human CRISPR/Cas9 screens in some datasets. | This supports the idea that loss of TRUB2 can strongly impair basic mitochondrial function and cell viability. | Antonicka et al., 2017-01-00 | (antonicka2017apseudouridinesynthase pages 1-2) |
| Important uncertainty | Some newer large-scale human tRNA mapping work reported that TRUB2 did not show noticeable enzymatic activity in their assay system, creating uncertainty about how broad or context-dependent its native substrate range is. | This does not negate earlier mitochondrial evidence, but suggests TRUB2 activity may depend on cell type, RNA context, cofactors, localization, or assay design. | Xu et al., 2025-10-00 | (xu2025acomprehensivetrna pages 2-3) |
| Best current inference for Columba livia TRUB2 | The rock dove TRUB2 ortholog is most plausibly a mitochondrial TruB-family pseudouridine synthase acting on structured mitochondrial RNAs, most likely contributing to Ψ55 formation in selected mt-tRNAs and/or pseudouridylation of specific mitochondrial transcripts, thereby supporting mitochondrial translation and OXPHOS. | This inference is strong at the family/localization/mechanism level, but exact dove-specific substrates remain unverified experimentally. | Cross-study inference from mammalian orthologs | (mukhopadhyay2021mammaliannucleartrub1 pages 1-2, antonicka2017apseudouridinesynthase pages 1-2, antonicka2017apseudouridinesynthase pages 2-3, zucchini2003thehumantrub pages 1-2, lin2025mechanisticinsightinto pages 9-10, jedynakslyvka2021humanmitochondrialrna pages 9-11) |
Table: This table compiles the main experimentally supported and inferred features of mammalian TRUB2 that are most relevant for annotating the rock dove ortholog. It emphasizes localization, catalytic activity, substrate specificity, biological role, and the main uncertainties in the current literature.
Based on the comprehensive analysis of mammalian orthologs, the Columba livia TRUB2 gene product (A0A2I0M3K7) can be functionally annotated as a mitochondrial pseudouridine synthase that:
The precise native substrate repertoire of the Rock dove TRUB2 remains to be experimentally determined, but the high evolutionary conservation of the TruB family strongly supports the inference that it performs analogous functions to its mammalian counterparts in maintaining mitochondrial RNA integrity and supporting mitochondrial protein synthesis.
The functional understanding of TRUB2 derives primarily from mammalian studies including:
- Mukhopadhyay et al. (2021) RNA 27:66-79 - Demonstrated compartmentalization of Ψ55 synthase activities (mukhopadhyay2021mammaliannucleartrub1 pages 1-2, mukhopadhyay2021mammaliannucleartrub1 pages 2-3)
- Antonicka et al. (2017) EMBO Reports 18:28-38 - Identified the mitochondrial pseudouridine synthase module (antonicka2017apseudouridinesynthase pages 1-2, antonicka2017apseudouridinesynthase pages 2-3, antonicka2017apseudouridinesynthase pages 3-7)
- Zucchini et al. (2003) International Journal of Molecular Medicine 11:697-704 - First characterization of human TRUB family (zucchini2003thehumantrub pages 1-2)
- Jia et al. (2022) Nucleic Acids Research 50:9368-9381 - Detailed analysis of TRUB1 in mitochondrial tRNAs (jia2022humantrub1is pages 1-2)
- Xu et al. (2025) Nature Cell Biology 27:2186-2197 - Comprehensive tRNA Ψ mapping revealing context-dependent TRUB2 activity (xu2025acomprehensivetrna pages 2-3)
- Lin et al. (2025) RNA Biology 22:1-25 - Mechanistic insights into pseudouridylation (lin2025mechanisticinsightinto pages 9-10)
- Jedynak-Slyvka et al. (2021) International Journal of Molecular Sciences 22:7999 - Review of mitochondrial RNA modifications (jedynakslyvka2021humanmitochondrialrna pages 9-11)
References
(zucchini2003thehumantrub pages 1-2): Cinzia Zucchini, Pierluigi Strippoli, Alessia Biolchi, Rossella Solmi, Luca Lenzi, Pietro D'Addabbo, Paolo Carinci, and Luisa Valvassori. The human trub family of pseudouridine synthase genes, including the dyskeratosis congenita 1 gene and the novel member trub1. International journal of molecular medicine, 11 6:697-704, Jun 2003. URL: https://doi.org/10.3892/ijmm.11.6.697, doi:10.3892/ijmm.11.6.697. This article has 46 citations and is from a peer-reviewed journal.
(lin2025mechanisticinsightinto pages 9-10): Ting-Yu Lin, Yasmin Stone, and Sebastian Glatt. Mechanistic insight into the pseudouridylation of rna. RNA biology, 22 1:1-25, 2025. URL: https://doi.org/10.1080/15476286.2025.2541421, doi:10.1080/15476286.2025.2541421. This article has 6 citations and is from a peer-reviewed journal.
(mukhopadhyay2021mammaliannucleartrub1 pages 1-2): Shaoni Mukhopadhyay, Manisha Deogharia, and Ramesh C. Gupta. Mammalian nuclear trub1, mitochondrial trub2, and cytoplasmic pus10 produce conserved pseudouridine 55 in different sets of trna. RNA, 27:66-79, Oct 2021. URL: https://doi.org/10.1261/rna.076810.120, doi:10.1261/rna.076810.120. This article has 49 citations and is from a domain leading peer-reviewed journal.
(antonicka2017apseudouridinesynthase pages 1-2): Hana Antonicka, Karine Choquet, Zhen‐Yuan Lin, Anne‐Claude Gingras, Claudia L Kleinman, and Eric A Shoubridge. A pseudouridine synthase module is essential for mitochondrial protein synthesis and cell viability. EMBO reports, 18:28-38, Jan 2017. URL: https://doi.org/10.15252/embr.201643391, doi:10.15252/embr.201643391. This article has 213 citations and is from a highest quality peer-reviewed journal.
(mukhopadhyay2021mammaliannucleartrub1 pages 2-3): Shaoni Mukhopadhyay, Manisha Deogharia, and Ramesh C. Gupta. Mammalian nuclear trub1, mitochondrial trub2, and cytoplasmic pus10 produce conserved pseudouridine 55 in different sets of trna. RNA, 27:66-79, Oct 2021. URL: https://doi.org/10.1261/rna.076810.120, doi:10.1261/rna.076810.120. This article has 49 citations and is from a domain leading peer-reviewed journal.
(antonicka2017apseudouridinesynthase pages 2-3): Hana Antonicka, Karine Choquet, Zhen‐Yuan Lin, Anne‐Claude Gingras, Claudia L Kleinman, and Eric A Shoubridge. A pseudouridine synthase module is essential for mitochondrial protein synthesis and cell viability. EMBO reports, 18:28-38, Jan 2017. URL: https://doi.org/10.15252/embr.201643391, doi:10.15252/embr.201643391. This article has 213 citations and is from a highest quality peer-reviewed journal.
(jia2022humantrub1is pages 1-2): Zidong Jia, Feilong Meng, Hui Chen, Gao Zhu, Xincheng Li, Yunfan He, Liyao Zhang, Xiao He, Huisen Zhan, Mengquan Chen, Yanchun Ji, Meng Wang, and Min-Xin Guan. Human trub1 is a highly conserved pseudouridine synthase responsible for the formation of ψ55 in mitochondrial trnaasn, trnagln, trnaglu and trnapro. Nucleic Acids Research, 50:9368-9381, Aug 2022. URL: https://doi.org/10.1093/nar/gkac698, doi:10.1093/nar/gkac698. This article has 41 citations and is from a highest quality peer-reviewed journal.
(antonicka2017apseudouridinesynthase pages 3-7): Hana Antonicka, Karine Choquet, Zhen‐Yuan Lin, Anne‐Claude Gingras, Claudia L Kleinman, and Eric A Shoubridge. A pseudouridine synthase module is essential for mitochondrial protein synthesis and cell viability. EMBO reports, 18:28-38, Jan 2017. URL: https://doi.org/10.15252/embr.201643391, doi:10.15252/embr.201643391. This article has 213 citations and is from a highest quality peer-reviewed journal.
(jedynakslyvka2021humanmitochondrialrna pages 9-11): Marta Jedynak-Slyvka, Agata Jabczynska, and Roman J. Szczesny. Human mitochondrial rna processing and modifications: overview. International Journal of Molecular Sciences, 22:7999, Jul 2021. URL: https://doi.org/10.3390/ijms22157999, doi:10.3390/ijms22157999. This article has 82 citations.
(antonicka2017apseudouridinesynthase pages 7-8): Hana Antonicka, Karine Choquet, Zhen‐Yuan Lin, Anne‐Claude Gingras, Claudia L Kleinman, and Eric A Shoubridge. A pseudouridine synthase module is essential for mitochondrial protein synthesis and cell viability. EMBO reports, 18:28-38, Jan 2017. URL: https://doi.org/10.15252/embr.201643391, doi:10.15252/embr.201643391. This article has 213 citations and is from a highest quality peer-reviewed journal.
(xu2025acomprehensivetrna pages 2-3): Haiqi Xu, Linzhen Kong, Mengjie Li, Giuseppina Pisignano, Jingfei Cheng, Feng Feng, Parinaz Mehdipour, and Chun-Xiao Song. A comprehensive trna pseudouridine map uncovers targets dependent on human stand-alone pseudouridine synthases. Nature Cell Biology, 27:2186-2197, Oct 2025. URL: https://doi.org/10.1038/s41556-025-01803-w, doi:10.1038/s41556-025-01803-w. This article has 9 citations and is from a highest quality peer-reviewed journal.
id: A0A2I0M3K7
gene_symbol: A0A2I0M3K7
product_type: PROTEIN
status: COMPLETE
taxon:
id: NCBITaxon:8932
label: Columba livia
description: >-
TRUB2 is a mitochondrial pseudouridine synthase belonging to the TruB family that catalyzes
the site-specific isomerization of uridine to pseudouridine (Psi) in mitochondrial RNAs. In
mammals, TRUB2 functions as a tRNA pseudouridine-55 synthase, converting U55 in the TPC loop
of select mitochondrial tRNAs to Psi55, a modification that stabilizes tRNA tertiary
structure through base-pairing with the D-loop. TRUB2 localizes to mitochondrial RNA granules,
where it participates in a pseudouridine synthase module together with RPUSD3, RPUSD4,
FASTKD2, and other RNA-binding proteins. Beyond tRNA modification, TRUB2 contributes to
pseudouridylation of specific mitochondrial mRNAs (MT-CO1, MT-CO3). TRUB2-mediated RNA
modifications are essential for mitochondrial translation and oxidative phosphorylation complex
assembly; depletion of TRUB2 in human cells reduces synthesis of mtDNA-encoded polypeptides
and impairs ATP synthase assembly. The Columba livia ortholog (142 amino acids) contains
the conserved pseudouridine synthase II N-terminal domain (PF01509) and is classified
in the Trub2-specific InterPro family (IPR039048), supporting functional equivalence
with mammalian TRUB2.
existing_annotations:
- term:
id: GO:0001522
label: pseudouridine synthesis
evidence_type: IEA
original_reference_id: GO_REF:0000002
qualifier: involved_in
review:
summary: >-
Correct biological process. TRUB2 catalyzes pseudouridine formation in mitochondrial
tRNAs and mRNAs; pseudouridine synthesis is its core biological process. However, a
more specific term exists: GO:0070902 (mitochondrial tRNA pseudouridine synthesis)
better captures the primary process for this mitochondrial enzyme.
action: MODIFY
reason: >-
The general term is accurate but too broad. TRUB2 is specifically a mitochondrial
pseudouridine synthase; GO:0070902 (mitochondrial tRNA pseudouridine synthesis) is
the appropriate specific process based on mammalian ortholog evidence.
proposed_replacement_terms:
- id: GO:0070902
label: mitochondrial tRNA pseudouridine synthesis
- term:
id: GO:0003723
label: RNA binding
evidence_type: IEA
original_reference_id: GO_REF:0000002
qualifier: enables
review:
summary: >-
Correct but generic. As a pseudouridine synthase that acts directly on RNA substrates
(mitochondrial tRNAs and mRNAs), TRUB2 necessarily binds RNA. The TruB family
uses a substrate-flipping mechanism that requires direct RNA contact. However, RNA
binding is ancillary to the catalytic function and does not provide informative
annotation beyond what the pseudouridine synthase activity already implies.
action: KEEP_AS_NON_CORE
reason: >-
RNA binding is an inherent mechanistic property of this RNA-modifying enzyme, not
a distinct core function. It is accurate but uninformative beyond the primary
catalytic annotation.
- term:
id: GO:0006396
label: RNA processing
evidence_type: IEA
original_reference_id: GO_REF:0000002
qualifier: involved_in
review:
summary: >-
Pseudouridylation is a post-transcriptional RNA modification, which falls under the
umbrella of RNA processing. However, the more precise term GO:0009451 (RNA
modification) is already annotated and better captures the nature of TRUB2's
activity. RNA processing is overly broad and could imply splicing, cleavage, or
other processing events that TRUB2 does not perform.
action: MARK_AS_OVER_ANNOTATED
reason: >-
Too broad. GO:0009451 (RNA modification), which is already annotated, is the correct
parent-level process term. RNA processing implies a wider range of activities than
what TRUB2 performs.
- term:
id: GO:0009451
label: RNA modification
evidence_type: IEA
original_reference_id: GO_REF:0000002
qualifier: involved_in
review:
summary: >-
Correct general biological process. TRUB2 performs RNA modification (specifically
pseudouridylation). This is a valid parent term of the more specific pseudouridine
synthesis process. Since a more specific term (pseudouridine synthesis / mitochondrial
tRNA pseudouridine synthesis) is available and preferred, this annotation is
redundant but not incorrect.
action: KEEP_AS_NON_CORE
reason: >-
Accurate parent-level process term, but redundant given the more specific
pseudouridine synthesis annotation. Kept as non-core since it adds no specificity
beyond the more informative annotations.
- term:
id: GO:0009982
label: pseudouridine synthase activity
evidence_type: IEA
original_reference_id: GO_REF:0000002
qualifier: enables
review:
summary: >-
Correct molecular function. TRUB2 is a bona fide pseudouridine synthase that
catalyzes uridine-to-pseudouridine isomerization. However, a more specific term
exists: GO:0160148 (tRNA pseudouridine(55) synthase activity) precisely describes
the established enzymatic specificity of TRUB2 for the Psi55 position in tRNAs.
GO:0106029 (tRNA pseudouridine synthase activity) would also be appropriate as
an intermediate-specificity annotation.
action: MODIFY
reason: >-
The general pseudouridine synthase activity term is accurate but too broad. Based
on mammalian ortholog evidence, TRUB2 specifically catalyzes tRNA pseudouridine-55
formation; GO:0160148 (tRNA pseudouridine(55) synthase activity) captures this
specificity. The ProtNLM2 prediction review also noted that GO:0106029 (tRNA
pseudouridine synthase activity) is a more specific correct term.
proposed_replacement_terms:
- id: GO:0160148
label: tRNA pseudouridine(55) synthase activity
references:
- id: GO_REF:0000002
title: Gene Ontology annotation through association of InterPro records with GO terms
findings: []
- id: file:COLLI/A0A2I0M3K7/A0A2I0M3K7-deep-research-falcon.md
title: Deep research report on TRUB2 in Columba livia (falcon/Edison)
findings:
- statement: >-
TRUB2 is a mitochondrial pseudouridine synthase that catalyzes Psi55 formation in
mitochondrial tRNAs, localizes to mitochondrial RNA granules, and is essential for
mitochondrial translation and OXPHOS complex assembly.
supporting_text: >-
TRUB2 functions as a mitochondrial tRNA Psi55 synthase, catalyzing the formation of
pseudouridine at position 55 in the TPC loop of select mitochondrial tRNAs
reference_review:
relevance: HIGH
correctness: VERIFIED
review_notes: >-
Comprehensive research report synthesizing mammalian TRUB2 literature from multiple
high-quality sources (Antonicka et al. 2017, Mukhopadhyay et al. 2021, Jia et al. 2022).
Function inferred from conserved orthologs is well-supported.
core_functions:
- description: >-
Mitochondrial tRNA pseudouridine-55 synthase that catalyzes the isomerization of U55 to
Psi55 in the TPC loop of select mitochondrial tRNAs, stabilizing tRNA tertiary structure.
The enzyme requires a U54-A58 reverse Hoogsteen base pair for efficient catalysis. Also
contributes to pseudouridylation of specific mitochondrial mRNAs (MT-CO1, MT-CO3).
These modifications are essential for mitochondrial translation and oxidative
phosphorylation complex assembly.
molecular_function:
id: GO:0160148
label: tRNA pseudouridine(55) synthase activity
directly_involved_in:
- id: GO:0070902
label: mitochondrial tRNA pseudouridine synthesis
locations:
- id: GO:0005759
label: mitochondrial matrix
supported_by:
- reference_id: file:COLLI/A0A2I0M3K7/A0A2I0M3K7-deep-research-falcon.md
supporting_text: >-
TRUB2 functions as a mitochondrial tRNA Psi55 synthase, catalyzing the formation of
pseudouridine at position 55 in the TPC loop of select mitochondrial tRNAs