CCoAOMT

CCoAOMT stands for caffeoyl-CoA O-methyltransferase, an enzyme in plants that catalyzes the methylation of caffeoyl-CoA to feruloyl-CoA as part of the lignin biosynthesis branch of the phenylpropanoid pathway. The methyl group is donated by S-adenosyl-L-methionine, and the reaction typically requires a divalent metal ion such as Mg2+ (with Mn2+ supporting activity in some species). The enzyme releases CoA as a byproduct.

In the lignin biosynthetic pathway, caffeoyl-CoA is converted by CCoAOMT to feruloyl-CoA, a key intermediate that feeds into the production of monolignols such as coniferyl and sinapyl alcohols, which polymerize to form lignin in the plant cell wall. By controlling the methylation of caffeoyl-CoA, CCoAOMT influences the composition and properties of lignin, including the relative amounts of guaiacyl and syringyl units.

CCoAOMT is typically localized in the cytosol, and it belongs to a gene family with multiple isoforms in many plant species. Expression of CCoAOMT genes is often high in lignifying tissues such as developing xylem and other vasculature, and it can be regulated by developmental cues as well as environmental factors.

From a biotechnological perspective, altering CCoAOMT activity or expression can change lignin content and composition, impacting plant growth, digestibility for forage, and the efficiency of industrial processes such as pulping and biofuel production. CCoAOMT is distinct from caffeic acid O-methyltransferase (COMT), which acts on free caffeic acid rather than caffeoyl-CoA.