pcoumaroylCoA

p-Coumaroyl-CoA is the coenzyme A thioester of p-coumaric acid (4-hydroxycinnamic acid). It is an activated intermediate in the phenylpropanoid pathway of plants and some microorganisms, enabling subsequent enzymatic condensations that build hydroxycinnamyl esters, flavonoids, and lignin precursors.

Biosynthesis of p-coumaroyl-CoA occurs when p-coumaric acid is converted by 4-coumarate-CoA ligase (4CL) in a reaction that consumes ATP and CoA, yielding p-coumaroyl-CoA, AMP, and pyrophosphate. In plants this reaction is typically cytosolic and integrated with broader phenylpropanoid metabolism.

In metabolism, p-coumaroyl-CoA serves as a starter substrate for type III polyketide synthases such as chalcone synthase, which condenses it with three malonyl-CoA units to form naringenin chalcone, the first committed step in flavonoid biosynthesis. It is also a substrate for stilbene synthase, contributing to resveratrol and related stilbenoids, and participates in lignin biosynthesis through downstream hydroxycinnamoyl transfer and modification steps. Through these pathways, p-coumaroyl-CoA integrates primary carbon flux with a diverse set of secondary metabolites.

Occurrence and significance: p-coumaroyl-CoA is widely distributed in vascular plants and represents a central node linking primary metabolism to a broad array of phenylpropanoid compounds. It is a common target in metabolic engineering aimed at modifying lignin content, flavonoid production, or hydroxycinnamate esters.

See also: 4-coumarate-CoA ligase, chalcone synthase, stilbene synthase, lignin biosynthesis, phenylpropanoid pathway.