High impact information on 4CL2

• 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 [1].
• We used this substrate specificity code to create At4CL2 gain-of-function mutants [2].
• By increasing the space within the SBP we generated ferulic- and sinapic acid-activating At4CL2 variants [2].
• Increasing the hydrophobicity of the SBP resulted in At4CL2 variants with strongly enhanced conversion of cinnamic acid [2].
• Among these amino acids, representing the putative "substrate specificity motif," only one residue, Met(293), was not conserved in At4CL2, compared with At4CL1 and At4CL3, two isoforms using ferulate [3].

Biological context of 4CL2

• 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 [4].
• Also, At4CL1::GUS transgene silencing was confined to the transgene but At4CL2::GUS silencing extended to the endogenous At4CL2 gene [5].
• 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 [5].
• The At4CL2 mutant enzyme K540L carrying a point mutation in the catalytic center that is critical for adenylate intermediate formation was inactive in both p(4)A and diadenosine 5',5''',-P(1),P(4)-tetraphosphate synthesis [6].

Associations of 4CL2 with chemical compounds

• Substitution of Met(293) or Lys(320), another residue of the putative substrate specificity motif, which in the predicted three-dimensional structure is located in close proximity to Met(293), by smaller amino acids converted At4CL2 to an enzyme capable of using ferulate [3].
• These results indicate that the cinnamoyl-adenylate intermediate synthesized by At4CL2 not only functions as an intermediate in coenzyme A ester formation but can also act as a cocatalytic AMP-donor in (di)adenosine polyphosphate synthesis [6].

References