Disease relevance of 4CL1

• RESULTS: A pathway for stilbene biosynthesis was constructed in Escherichia coli with 4-coumaroyl CoA ligase 1 4CL1) from Arabidopsis thaliana and stilbene synthase (STS) cloned from Arachis hypogaea [1].
• No activation of 4CL expression was observed in a compatible interaction caused by a Pseudomonas syringae pv. maculicola strain without avrB [2].

High impact information on 4CL1

• Phylogenetic analysis suggests an early evolutionary and functional divergence of three of the four gene family members, At4CL2-4, whereas At4CL1 appears to have originated much later by duplication of its structurally and functionally closest relative, At4CL2 [3].
• The 4-coumarate:CoA ligase gene family in Arabidopsis thaliana comprises one rare, sinapate-activating and three commonly occurring isoenzymes [3].
• To reveal the structural principles determining substrate specificity of 4-coumarate:CoA ligase (4CL), the crystal structure of the phenylalanine activation domain of gramicidin S synthetase was used as a template for homology modeling [4].
• While both enzymes convert 4-coumarate, only At4CL1 is also capable of converting ferulate [5].
• Based on their enzymatic properties, expression characteristics and evolutionary relationships, At4CL3 is likely to participate in the biosynthetic pathway leading to flavonoids whereas At4CL1 and At4CL2 are probably involved in lignin formation and in the production of additional phenolic compounds other than flavonoids [6].

Biological context of 4CL1

• We investigated in detail the wound-induced expression of At4CL1-At4CL4, and found that At4CL1 and At4CL2 mRNA accumulation follows biphasic kinetics over a period of 72 h, while At4CL4 expression is rapidly activated for a period of at least 12 h before declining [7].
• A recent in silico analysis revealed that the Arabidopsis genome has 14 genes annotated as putative 4-coumarate:CoA ligase isoforms or homologues [8].
• Transgenic Arabidopsis plants containing the At4CL1 or At4CL2 promoter fused to the beta-glucuronidase (GUS) reporter gene show developmentally regulated GUS expression in the xylem tissues of the root and shoot [9].
• The predicted amino acid sequence is similar to those of other cloned 4CL genes [2].
• The timing of 4CL activation was identical to the previously observed activation of PAL gene expression in this interaction [2].

Associations of 4CL1 with chemical compounds

• Of the 11 putative His6-tagged 4CLs, isoform At4CL1 best utilized p-coumaric, caffeic, ferulic and 5-hydroxyferulic acids as substrates, whereas At4CL2 readily transformed p-coumaric and caffeic acids into the corresponding CoA esters, while ferulic and 5-hydroxyferulic acids were converted quite poorly [8].
• Indeed, both At4CL1 and At4CL5 most effectively utilized 5-hydroxyferulic acid with kenz approximately 10-fold higher than that for At4CL2 and At4CL3 [8].
• Substitution of 4CL1 with a homologous enzyme, 4CL4, with a preference for ferulic acid over 4-coumaric acid, had no effect on the conversion of ferulic acid [1].
• Mutational analysis of 4-coumarate:CoA ligase identifies functionally important amino acids and verifies its close relationship to other adenylate-forming enzymes [10].

Analytical, diagnostic and therapeutic context of 4CL1

• Northern blots showed that 4CL expression was activated early during seedling development [2].
• Southern blot analysis indicated that 4CL is single-copy gene in Arabidopsis [2].

References