MONBRDRAFT_1233 encodes the Warts/LATS-family (NDR subgroup, AGC group) serine/threonine protein kinase of the strictly unicellular choanoflagellate Monosiga brevicollis. The UniProt entry (A9UVF9, 380 residues) is a fragment from the draft genome assembly, truncated at both ends: it covers the protein kinase domain (residues 78-368, with the ATP-binding lysine K107 and catalytic aspartate D201) plus short flanking segments, but lacks the N-terminal region that in LATS kinases binds MOB1 and the AGC-kinase C-terminal extension with the hydrophobic-motif phosphorylation site. It is the only M. brevicollis member of the PANTHER Warts subfamily, which includes human LATS1/2 and Drosophila Warts. In animals Warts/LATS, activated by Hippo, phosphorylates the coactivator Yorkie/YAP on HXRXXS motifs and keeps it in the cytoplasm. M. brevicollis appears to have an eroded version of this pathway: its Hippo gene model is predicted to be truncated at the start of the kinase domain, and its Yorkie homolog has no consensus Warts phosphorylation motif. Nothing is known experimentally about this protein; its kinase activity, substrates, regulators and localization have not been examined.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0000082 G1/S transition of mitotic cell cycle | IBA GO_REF:0000033 | MARK AS OVER ANNOTATED | Summary: IBA from the PAINT IBD at PTN002390470, the Warts/LATS "Metazoa-Choanoflagellida" node, seeded by mouse Lats2 and human LATS2 cell-cycle evidence. There are no cell-cycle data for M. brevicollis Warts. In the closest tested choanoflagellate, S. rosetta, warts knockout cells proliferate more slowly, the reverse of the animal loss-of-function phenotype [DOI:10.1101/2024.07.13.603360]. Reason: G1/S transition is a eukaryote-wide process, so this is not a taxon violation, and choanoflagellates do have a mitotic cell cycle. But the IBD rests on a vertebrate LATS2 role, and nothing places choanoflagellate Warts in G1/S control: S. rosetta warts loss slows rather than accelerates proliferation, and in M. brevicollis the upstream kinase and the Yorkie phosphorylation sites appear to be lost. Kept as an over-annotation rather than removed, consistent with the S. rosetta warts review, because no data contradict the node placement directly. Propagation Review Root cause: PROPAGATION BAD Failure modes: CONTEXT OR TISSUE MISMATCH Sources checked: PANTHER:PTN002390470 · Warts/LATS, Metazoa-Choanoflagellida node SUPPORTS SOURCE BUT NOT TARGET IBD seeded by vertebrate LATS2 cell-cycle evidence (mouse Lats2, human LATS2); sound for vertebrates, no evidence the role extends to choanoflagellates. Supporting Evidence: DOI:10.1101/2024.07.13.603360 On the other hand, hippopac1 and warts pac1 KO clones proliferated markedly slower DOI:10.1101/2024.07.13.603360 down proliferation in S. rosetta, which is the opposite of their animal loss-of-function phenotype |
| GO:0000166 nucleotide binding | IEA GO_REF:0000104 | KEEP AS NON CORE | Summary: UniRule assignment from the protein kinase ATP-binding signature (ATP-binding residue K107). Reason: True but uninformative parent of ATP binding, itself part of the kinase activity. No binding measurements exist. Supporting Evidence: file:MONBE/MONBRDRAFT_1233/MONBRDRAFT_1233-uniprot.txt PROSITE; PS00107; PROTEIN_KINASE_ATP; 1. |
| GO:0004672 protein kinase activity | IEA GO_REF:0000002 | KEEP AS NON CORE | Summary: InterPro2GO from the Ser/Thr kinase active-site signature (IPR008271); the catalytic aspartate D201 is present in the fragment. Reason: Correct, but the more specific protein serine/threonine kinase activity term is also present and better describes a Warts/LATS AGC kinase. Supporting Evidence: file:MONBE/MONBRDRAFT_1233/MONBRDRAFT_1233-uniprot.txt PROSITE; PS00108; PROTEIN_KINASE_ST; 1. |
| GO:0004674 protein serine/threonine kinase activity | IBA GO_REF:0000033 | ACCEPT | Summary: IBA from the PAINT IBD at PTN000683254, a deep AGC-kinase node whose descendants include animal, fungal and plant Ser/Thr kinases with experimental activity, including human LATS1/2 and Drosophila wts. A9UVF9 is in PANTHER subfamily PTHR24356:SF418 (Warts) and retains an intact kinase domain with the ATP-binding lysine and catalytic aspartate. In animals Warts/LATS phosphorylates Yorkie/YAP on HXRXXS motifs [PMID:35659869]. Reason: This is the core molecular activity of a Warts/LATS kinase. The IBD sits at a deep node that the M. brevicollis protein clearly descends from, and the catalytic residues are conserved, so there is no sign of loss of activity. The gene model is a fragment lacking the AGC C-terminal hydrophobic motif needed for full activation of animal LATS kinases; if this reflects the real gene rather than the draft assembly, regulation could differ, but the catalytic domain is intact. Activity has not been assayed for this protein. Propagation Review Root cause: NO FAILURE CORE Sources checked: PANTHER:PTN000683254 · AGC kinase node, PTHR24356 SUPPORTS TRANSFER Deep IBD backed by experimental kinase activity across many AGC kinases; the target keeps the catalytic residues. Supporting Evidence: file:MONBE/MONBRDRAFT_1233/MONBRDRAFT_1233-uniprot.txt PANTHER; PTHR24356:SF418; SERINE_THREONINE-PROTEIN KINASE WARTS; 1. file:MONBE/MONBRDRAFT_1233/MONBRDRAFT_1233-uniprot.txt PROSITE; PS00108; PROTEIN_KINASE_ST; 1. PMID:35659869 In mammals and in Drosophila, YAP/TAZ/Yorkie is regulated by cytoplasmic sequestration in response to phosphorylation of HXRXXS motifs by the LATS/Warts kinases (Zheng and Pan, 2019). |
| GO:0004674 protein serine/threonine kinase activity | IEA GO_REF:0000120 | ACCEPT | Summary: Combined IEA (EC 2.7.11.1 from the PROSITE Ser/Thr active-site rule, UniRule), duplicating the IBA for the same term. Reason: Same assertion as the accepted IBA row, from independent domain-based methods; the catalytic residues are retained. Supporting Evidence: file:MONBE/MONBRDRAFT_1233/MONBRDRAFT_1233-uniprot.txt PROSITE; PS00108; PROTEIN_KINASE_ST; 1. |
| GO:0005524 ATP binding | IEA GO_REF:0000120 | ACCEPT | Summary: Domain-based assignment from the protein kinase domain and its ATP-binding signature (K107). Reason: Kinase domain with the conserved ATP-binding lysine; ATP binding is required for the predicted catalytic activity. Sound domain-level inference, not measured. Supporting Evidence: file:MONBE/MONBRDRAFT_1233/MONBRDRAFT_1233-uniprot.txt InterPro; IPR017441; Protein_kinase_ATP_BS. |
| GO:0005737 cytoplasm | IEA GO_REF:0000120 | ACCEPT | Summary: ARBA rule and UniProt subcellular-location keyword. Warts/LATS kinases act in the cytoplasm in animals, and Capsaspora coWts keeps its Yorkie homolog cytoplasmic [PMID:38517944]. No localization data exist for the M. brevicollis protein. Reason: Cytoplasm is the expected compartment for a Warts/LATS kinase and is broad enough to be safe without direct data. Accepted as a homology-based location, as for S. rosetta warts. Supporting Evidence: file:MONBE/MONBRDRAFT_1233/MONBRDRAFT_1233-uniprot.txt SUBCELLULAR LOCATION: Cytoplasm PMID:38517944 Together, these results show that the Capsaspora Hippo kinase cascade regulates coYki by cytoplasmic sequestration, indicating a premetazoan origin of this regulatory activity of the Hippo pathway. |
| GO:0016301 kinase activity | IEA GO_REF:0000104 | KEEP AS NON CORE | Summary: UniRule assignment of the general kinase activity parent term. Reason: True but redundant with the more specific protein serine/threonine kinase activity annotation. Supporting Evidence: file:MONBE/MONBRDRAFT_1233/MONBRDRAFT_1233-uniprot.txt PROSITE; PS50011; PROTEIN_KINASE_DOM; 1. |
| GO:0016740 transferase activity | IEA GO_REF:0000104 | KEEP AS NON CORE | Summary: UniRule assignment of the very general transferase activity term. Reason: True (a kinase transfers phosphate) but too general to be informative. Kept as a non-core parent of protein serine/threonine kinase activity. Supporting Evidence: file:MONBE/MONBRDRAFT_1233/MONBRDRAFT_1233-uniprot.txt PROSITE; PS50011; PROTEIN_KINASE_DOM; 1. |
| GO:0035329 hippo signaling | IBA GO_REF:0000033 | UNDECIDED | Summary: IBA from the PAINT IBD at PTN002390470 (Warts/LATS, "Metazoa-Choanoflagellida"), seeded by Drosophila wts, mouse Lats1/2 and human LATS1/2. The node placement is supported by evidence that the Hippo-Warts-Yorkie cascade predates animals: in Capsaspora, loss of the Warts homolog lets the Yorkie homolog enter the nucleus [PMID:38517944], and the S. rosetta Yorkie homolog carries four Warts motifs [PMID:38729842]. But M. brevicollis itself shows signs of losing the pathway: a Hpo homolog was not found in its genome [PMID:22832104], the Hippo gene model that was later identified is predicted to be truncated at the start of its kinase domain, and M. brevicollis Yorkie lacks a consensus HXRXXS Warts motif [PMID:38729842]. No experiment has addressed Warts function in M. brevicollis. Reason: The IBD itself is sound and was accepted for S. rosetta warts. The question here is whether this particular descendant still takes part in the cascade. M. brevicollis has target-specific comparative-genomic evidence of divergence (no intact Hippo, no consensus Warts site on Yorkie), and the authors suggest it may have lost Hippo regulation of Yorkie. That argues against inheritance in this lineage, but it is a sequence-based prediction from a draft assembly that also produced this fragmentary Warts model, and Warts could be activated by other upstream kinases or act on other substrates. Neither accepting nor removing is justified without data, so the row is left undecided and not counted as a core function. Propagation Review Root cause: UNRESOLVED Failure modes: FUNCTIONAL DIVERGENCE Sources checked: PANTHER:PTN002390470 · Warts/LATS, Metazoa-Choanoflagellida node UNRESOLVED IBD well supported by fly and mammalian Warts/LATS and consistent with Capsaspora data, but M. brevicollis shows predicted loss of Hippo and of Warts sites on Yorkie, so inheritance in this lineage is uncertain. Supporting Evidence: PMID:38729842 Further, the M. brevicollis Hippo gene contains an insertion that is predicted to truncate the protein at the beginning of the kinase domain PMID:38729842 Thus M. brevicollis may be an example of an organism that encodes a Yorkie ortholog but has lost the capacity to be regulated by Hippo pathway signaling. PMID:22832104 except for M. brevicollis and non-chytrid fungi, most likely due to secondary loses PMID:38517944 Together, these results show that the Capsaspora Hippo kinase cascade regulates coYki by cytoplasmic sequestration, indicating a premetazoan origin of this regulatory activity of the Hippo pathway. |
| GO:0043065 positive regulation of apoptotic process | IBA GO_REF:0000033 | MARK AS OVER ANNOTATED | Summary: IBA from the IBD at PTN002390470 whose only seed is Drosophila wts, where Warts promotes apoptosis by inactivating Yorkie and so lowering expression of the caspase inhibitor diap1. No cell death has been studied in relation to Warts in any choanoflagellate. Reason: The term is not excluded for opisthokonts, so this is not a taxon violation. But the donor biology is Yorkie-dependent control of an animal anti-apoptotic programme in growing tissue. There is no evidence that choanoflagellate Warts regulates apoptosis, choanoflagellate Yorkie homologs may not bind TEAD, and in M. brevicollis Yorkie lacks consensus Warts sites. Not removed, because no data contradict it; consistent with the S. rosetta warts review. Propagation Review Root cause: PROPAGATION BAD Failure modes: CONTEXT OR TISSUE MISMATCH Sources checked: PANTHER:PTN002390470 · Warts/LATS, Metazoa-Choanoflagellida node SUPPORTS SOURCE BUT NOT TARGET Seeded by Drosophila wts tissue-growth and apoptosis phenotypes; no choanoflagellate data on apoptosis. Supporting Evidence: PMID:38729842 The degree to which choanoflagellate Yorkie orthologs interact with Sd/TEAD proteins is therefore currently unclear PMID:38729842 Thus M. brevicollis may be an example of an organism that encodes a Yorkie ortholog but has lost the capacity to be regulated by Hippo pathway signaling. |
| GO:0046620 regulation of organ growth | IBA GO_REF:0000033 | REMOVE | Summary: IBA from the IBD at PTN002390470 seeded by mouse Lats2. GO defines the term as modulating the growth of an organ of an organism; it is a child of regulation of developmental growth. M. brevicollis is strictly unicellular [PMID:18273011] and has no organs. The GO taxon constraints on this term do not exclude choanoflagellates, so nothing in the pipeline blocks the transfer. Reason: An organ is a multicellular structure of an animal or plant body. A strictly unicellular organism has none, so the term cannot be true of this protein whatever its function. The mouse source annotation is sound; the fault is that an organ-level outcome was placed at a node that includes unicellular choanoflagellates. Removed, as for S. rosetta warts; no replacement is proposed, because M. brevicollis does not even form rosettes. Propagation Review Root cause: PROPAGATION BAD Failure modes: LINEAGE OR TAXON MISMATCH Sources checked: PANTHER:PTN002390470 · Warts/LATS, Metazoa-Choanoflagellida node SUPPORTS SOURCE BUT NOT TARGET Organ-growth IBD seeded by mouse Lats2; valid for animals, but the node spans choanoflagellates, which have no organs. Supporting Evidence: PMID:18273011 Although M. brevicollis is strictly unicellular, other choanoflagellates facultatively form colonies |
| GO:0071944 cell periphery | IEA GO_REF:0000117 | UNDECIDED | Summary: ARBA machine-learning rule. In animals Warts/LATS is recruited to the plasma membrane by MOB1 and upstream adaptors during activation; the MOB1-binding region is missing from this fragmentary gene model. Localization of M. brevicollis Warts has not been examined. Reason: A membrane-proximal pool is plausible for a Warts/LATS kinase, but there are no data for or against it, and the rule is not specific to the LATS clade. Same call as for S. rosetta warts. Supporting Evidence: file:MONBE/MONBRDRAFT_1233/MONBRDRAFT_1233-uniprot.txt SUBCELLULAR LOCATION: Cytoplasm |
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Download this section (compressed HTML)Q: Is the 380-residue MONBRDRAFT_1233 model a draft-assembly artefact, or does the M. brevicollis Warts gene really lack the N-terminal MOB1-binding region and the AGC C-terminal hydrophobic motif? Transcript evidence (RNA-seq or RACE) would settle this.
Q: Is the M. brevicollis Hippo gene truly truncated, or is this also an assembly error? If Hippo is lost, which kinases (if any) activate Warts in M. brevicollis?
Q: Without consensus HXRXXS sites on its Yorkie homolog, what does M. brevicollis Warts phosphorylate? Is the kinase under relaxed constraint compared with S. rosetta warts?
Q: Should PAINT place the organ-growth (GO:0046620) and apoptosis IBDs at a metazoan rather than the Metazoa-plus-choanoflagellate node, or should GO add taxon constraints restricting organ-level growth terms to taxa with organs?
Experiment: Map M. brevicollis RNA-seq reads or perform 5' and 3' RACE on MONBRDRAFT_1233 to determine the full open reading frame, and check for MOB1-binding and hydrophobic-motif regions.
Hypothesis: The MONBRDRAFT_1233 gene encodes a full-length Warts/LATS kinase not captured by the draft gene model.
Type: transcript mapping
Experiment: In vitro kinase assay of recombinant full-length M. brevicollis Warts (wild type versus K107A) on a generic AGC substrate and on recombinant M. brevicollis and S. rosetta Yorkie, with phospho-site mapping by mass spectrometry.
Hypothesis: M. brevicollis Warts is an active kinase that does not phosphorylate its Yorkie homolog.
Type: biochemical kinase assay
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