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this with annotations you find in gene/protein databases, but these can be outdated or inaccurate.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.
UGT74C1 (UniProt Q9SKC1; gene locus At2g31790) encodes a UDP-glycosyltransferase belonging to the plant family-1 superfamily, specifically the UGT74 subfamily. These enzymes catalyze the transfer of sugar moieties from activated UDP-sugars to a range of acceptor molecules, thereby altering their stability, solubility, and biological activity (kenawy2017characterizationoftwo pages 35-40, ross2001higherplantglycosyltransferases pages 3-4).
UGT74C1 functions primarily as a UDP-glucose:thiohydroximate S-glucosyltransferase, catalyzing an essential step in the biosynthesis of glucosinolates. Its major role is to transfer glucose from UDP-glucose to the sulfur atom of thiohydroximate intermediates, forming desulfoglucosinolate. This step is a penultimate reaction before sulfate addition by dedicated sulfotransferases, forming mature glucosinolates (yaya2014phytoalexinsandother pages 45-51, grubb2004arabidopsisglucosyltransferaseugt74b1 pages 1-2, vik2024standardflowtargetedproteomics pages 3-5, vik2024standardflowtargetedproteomics pages 1-2).
UGT74C1 is especially implicated in the biosynthesis of aliphatic (methionine-derived) glucosinolates. Both UGT74C1 and its paralog UGT74B1 can catalyze this reaction, but recent evidence distinguishes their regulation and potential substrate preferences (see Section 5).
The most significant recent study is Vik 2024 (vik2024standardflowtargetedproteomics pages 3-5, vik2024standardflowtargetedproteomics pages 1-2), which utilized standard-flow liquid chromatography–selected reaction monitoring (LC–SRM) targeted proteomics to quantify UGT74C1 protein levels in Arabidopsis glucosinolate pathways. Key insights include:
Whereas UGT74B1 appears to function across both aliphatic and indole glucosinolate biosynthesis (not affected in myb28/29 but decreased in myb34/51/122 and myc2/3/4 backgrounds), UGT74C1's protein abundance is specifically sensitive to loss of aliphatic-pathway regulators. This indicates possible substrate or pathway branch specificity, though direct experimental kinetics for UGT74C1 remain unavailable (grubb2004arabidopsisglucosyltransferaseugt74b1 pages 2-4, vik2024standardflowtargetedproteomics pages 3-5, kenawy2017characterizationoftwo pages 35-40).
Understanding and manipulating UGT74C1 is relevant for metabolic engineering of glucosinolate content in crops. Synthetic biology efforts targeting tailored glucosinolate production (e.g., for improved pest resistance or nutritional profiles) must consider pathway branch point regulation and differential post-transcriptional control of core enzymes, including UGT74C1 (vik2024standardflowtargetedproteomics pages 3-5).
The latest expert analysis (see Vik 2024) underlines the importance of measuring protein, not just transcript, for a correct pathway understanding. Family-level comparative genomics and proteomics both warn that UGT function cannot be inferred solely from primary sequence or phylogenetic affiliation, reinforcing the need for direct enzyme characterization (kenawy2017characterizationoftwo pages 35-40).
Limitations: Direct kinetic constants, a complete panel of physiological substrates, and in planta fluorescent localization for UGT74C1 itself remain to be reported in peer-reviewed literature.
Below is a table summarizing the functional annotation, pathway role, regulation, and experimental support for UGT74C1:
| Category | UGT74C1 summary | Evidence and interpretation |
|---|---|---|
| Identity | UDP-glycosyltransferase 74C1; gene UGT74C1; ordered locus At2g31790; UniProt Q9SKC1 | Identifiers match the UniProt target specified for this report; the literature also associates UGT74C1 with Arabidopsis glucosinolate biosynthesis (vik2024standardflowtargetedproteomics pages 12-15, vik2024standardflowtargetedproteomics pages 3-5) |
| Organism | Arabidopsis thaliana (mouse-ear cress) | The 2024 targeted-proteomics study measured UGT74C1 as one of the enzymes in A. thaliana glucosinolate pathways (vik2024standardflowtargetedproteomics pages 3-5, vik2024standardflowtargetedproteomics pages 1-2) |
| Protein family and domains | Plant family-1 UDP-dependent glycosyltransferase, UGT74 subfamily; assigned to phylogenetic group L; contains the UDP-glycosyltransferase/PSPG-type machinery represented by InterPro IPR002213, IPR035595 and Pfam PF00201 | UGT74C1 and UGT74B1 group with family-1 UGTs associated with specialized-metabolite glycosylation, including thiohydroximate metabolism; phylogeny alone is insufficient to establish exact specificity (kenawy2017characterizationoftwo pages 35-40) |
| Primary reaction | Transfers glucose from UDP-glucose to the sulfur of a glucosinolate-pathway thiohydroximate, producing a desulfoglucosinolate and UDP; functionally, this is an S-glucosylation step | UGT74 enzymes act after thiohydroximate formation and before terminal sulfation (yaya2014phytoalexinsandother pages 45-51, grubb2004arabidopsisglucosyltransferaseugt74b1 pages 1-2); Vik places the UGT74B1/UGT74C1-catalyzed step immediately after SUR1 (vik2024standardflowtargetedproteomics pages 3-5) |
| Acceptor substrates | Physiological substrate class: glucosinolate-pathway thiohydroximates. Evidence supports a preferential role in intermediates of aliphatic, chain-elongated-methionine-derived glucosinolates; a complete quantitative substrate panel or definitive single preferred acceptor is not established in the cited material | Protein abundance responds to loss of aliphatic-glucosinolate regulators MYB28/MYB29 but not to loss of indole-pathway MYB34/MYB51/MYB122, supporting aliphatic-pathway specialization (vik2024standardflowtargetedproteomics pages 3-5). Exact specificity should not be inferred solely from UGT74 phylogeny (kenawy2017characterizationoftwo pages 35-40) |
| Products | Corresponding desulfoglucosinolate(s), which are subsequently O-sulfated to mature glucosinolates | Desulfoglucosinolate formation is the penultimate core-assembly stage; sulfotransferases then add sulfate (yaya2014phytoalexinsandother pages 45-51, grubb2004arabidopsisglucosyltransferaseugt74b1 pages 1-2) |
| Pathway position | Glucosinolate core-structure biosynthesis: amino-acid-derived oxime → activated intermediate/glutathione conjugate → SUR1-generated thiohydroximate → UGT74C1-dependent S-glucosylation → desulfoglucosinolate → sulfotransferase-dependent glucosinolate | Vik identifies UGT74B1 or UGT74C1 as catalyzing the step immediately following SUR1 and preceding SOT16/SOT17/SOT18 activity (vik2024standardflowtargetedproteomics pages 3-5) |
| Biological role | Contributes to biosynthesis of sulfur- and nitrogen-containing glucosinolate defense metabolites, particularly the aliphatic class | Glucosinolates are characteristic Brassicales defense compounds whose hydrolysis products deter herbivores and pathogens; UGT74C1 supplies their conserved thioglucose-containing core rather than catalyzing downstream hydrolysis (vik2024standardflowtargetedproteomics pages 1-2, ross2001higherplantglycosyltransferases pages 3-4) |
| Relationship to UGT74B1 | Partially overlapping paralogs: either UGT74B1 or UGT74C1 can catalyze the post-SUR1 glucosylation. UGT74B1 behaves more like an enzyme shared between aliphatic and indole pathways, whereas UGT74C1 shows stronger association with the aliphatic pathway | UGT74B1 transcript/protein patterns resemble shared-pathway enzymes; its abundance is unaffected in the aliphatic-regulator mutant but reduced in indole and MYC mutants. UGT74C1 protein instead decreases in the aliphatic myb28/29 and global myc2/3/4 mutants, but not in myb34/51/122 (vik2024standardflowtargetedproteomics pages 3-5) |
| UGT74B1 biochemical benchmark | Recombinant UGT74B1 glucosylates phenylacetothiohydroximic acid to desulfobenzylglucosinolate; reported acceptor Kₘ ≈ 5.8 µM and no activity toward IAA, phenylacetic acid or salicylic acid under the tested conditions | These measurements directly characterize UGT74B1, not UGT74C1, and therefore support the shared reaction class but must not be transferred quantitatively to UGT74C1 (grubb2004arabidopsisglucosyltransferaseugt74b1 pages 2-4) |
| Transcription-factor regulation | Associated with the aliphatic R2R3-MYB module (MYB28/MYB29) and the broader jasmonate-responsive bHLH module (MYC2/MYC3/MYC4) | UGT74C1 protein was significantly reduced in myb28/29 and myc2/3/4, but not in the indole-pathway myb34/51/122 mutant (vik2024standardflowtargetedproteomics pages 3-5) |
| Transcript–protein coupling | Regulation cannot be inferred reliably from transcript abundance alone: UGT74C1 transcripts decreased similarly in all three transcription-factor mutant backgrounds, while protein abundance distinguished aliphatic from indole regulator mutants | This divergence indicates post-transcriptional and/or post-translational control of UGT74C1 abundance (vik2024standardflowtargetedproteomics pages 3-5, vik2024standardflowtargetedproteomics pages 1-2) |
| Methyl-jasmonate response | After MeJA treatment, measured glucosinolate-pathway transcripts increased within 1 hour, but corresponding proteins generally did not increase; UGT74C1 protein was significantly lower at 25 hours | The experiment revealed temporal uncoupling among transcripts, proteins and metabolites, arguing against interpreting rapid UGT74C1 mRNA induction as immediate enzyme accumulation (vik2024standardflowtargetedproteomics pages 3-5, vik2024standardflowtargetedproteomics pages 1-2) |
| 2024 technical advance | Standard-flow LC–selected-reaction-monitoring targeted proteomics quantified UGT74C1 among 12 glucosinolate-biosynthetic enzymes and compared protein with transcript abundance in the same biological samples | The method provided direct pathway-enzyme measurements using triple-quadrupole MS and exposed regulatory behavior missed by transcript profiling alone; the report is a bioRxiv preprint, so its conclusions await peer-reviewed confirmation (vik2024standardflowtargetedproteomics pages 3-5, vik2024standardflowtargetedproteomics pages 1-2) |
| Subcellular localization | Best-supported assignment is a soluble cytosolic enzyme, but this remains principally a prediction rather than direct UGT74C1 imaging evidence | Arabidopsis UGT sequence analyses found no secretion signal or membrane-targeting motif, supporting cytoplasmic localization for UGT74C1 and related plant UGTs (ross2001higherplantglycosyltransferases pages 3-4) |
| Evidence limitations | The pathway assignment is strong, but the available cited evidence does not provide UGT74C1-specific kinetic constants, a comprehensive purified-enzyme substrate screen, a solved experimental structure or direct fluorescence-based localization | Family-level and paralog evidence should therefore be separated from direct UGT74C1 measurements; the strongest recent direct evidence concerns protein abundance and pathway regulation rather than catalytic kinetics (vik2024standardflowtargetedproteomics pages 3-5, kenawy2017characterizationoftwo pages 35-40) |
Table: This table integrates the verified identity, catalytic role, pathway placement, localization evidence and regulation of Arabidopsis UGT74C1. It distinguishes direct UGT74C1 findings—especially the 2024 targeted-proteomics results—from biochemical evidence obtained for its paralog UGT74B1.
Additional references support pathway placement and gene family context; database and annotation evidence can be found in UniProt Q9SKC1 and TAIR At2g31790.
This report integrates current authoritative findings, prioritizing experimental details and post-genomics insights into UGT74C1's specialized role in glucosinolate assembly and plant defense.
References
(kenawy2017characterizationoftwo pages 35-40): Ahmed Kenawy. Characterization of two udp glycosyltransferase genes from hybrid poplar. ArXiv, Jan 2017. URL: https://doi.org/10.14288/1.0340544, doi:10.14288/1.0340544. This article has 1 citations.
(ross2001higherplantglycosyltransferases pages 3-4): Joe Ross, Yi Li, Eng-Kiat Lim, and Dianna J Bowles. Higher plant glycosyltransferases. Genome Biology, 2:reviews3004.1-reviews3004.6, Feb 2001. URL: https://doi.org/10.1186/gb-2001-2-2-reviews3004, doi:10.1186/gb-2001-2-2-reviews3004. This article has 689 citations and is from a highest quality peer-reviewed journal.
(yaya2014phytoalexinsandother pages 45-51): E Yaya. Phytoalexins and other antifungal metabolites from crucifers: isolation, synthesis and biosynthesis. Unknown journal, 2014.
(grubb2004arabidopsisglucosyltransferaseugt74b1 pages 1-2): C. Douglas Grubb, Brandon J. Zipp, Jutta Ludwig‐Müller, Makoto N. Masuno, Tadeusz F. Molinski, and Steffen Abel. Arabidopsis glucosyltransferase ugt74b1 functions in glucosinolate biosynthesis and auxin homeostasis. The Plant journal : for cell and molecular biology, 40 6:893-908, Dec 2004. URL: https://doi.org/10.1111/j.1365-313x.2004.02261.x, doi:10.1111/j.1365-313x.2004.02261.x. This article has 355 citations.
(vik2024standardflowtargetedproteomics pages 3-5): Daniel Vik. Standard-flow targeted proteomics for quantification of enzymes in glucosinolate biosynthetic pathways. bioRxiv, Nov 2024. URL: https://doi.org/10.1101/2024.11.15.623753, doi:10.1101/2024.11.15.623753. This article has 0 citations.
(vik2024standardflowtargetedproteomics pages 1-2): Daniel Vik. Standard-flow targeted proteomics for quantification of enzymes in glucosinolate biosynthetic pathways. bioRxiv, Nov 2024. URL: https://doi.org/10.1101/2024.11.15.623753, doi:10.1101/2024.11.15.623753. This article has 0 citations.
(grubb2004arabidopsisglucosyltransferaseugt74b1 pages 2-4): C. Douglas Grubb, Brandon J. Zipp, Jutta Ludwig‐Müller, Makoto N. Masuno, Tadeusz F. Molinski, and Steffen Abel. Arabidopsis glucosyltransferase ugt74b1 functions in glucosinolate biosynthesis and auxin homeostasis. The Plant journal : for cell and molecular biology, 40 6:893-908, Dec 2004. URL: https://doi.org/10.1111/j.1365-313x.2004.02261.x, doi:10.1111/j.1365-313x.2004.02261.x. This article has 355 citations.
(vik2024standardflowtargetedproteomics pages 12-15): Daniel Vik. Standard-flow targeted proteomics for quantification of enzymes in glucosinolate biosynthetic pathways. bioRxiv, Nov 2024. URL: https://doi.org/10.1101/2024.11.15.623753, doi:10.1101/2024.11.15.623753. This article has 0 citations.