Abstract:

There is a 4CL gene family in most vascular plants. The different 4CL members which expressed differentially in plants participated in the different phenylpropanoid metabolism. The express of 4CL was mainly regulated by development stage, and it also was activated by many environmental factors such as damages, pathogenic intrusion and ultraviolet radiation. 4CL exists distinct substrate preference and specificities. The spatial restrictions of the binding groove rather than specific interactions between the substrate and amino acid residues of the polypeptide chain may be decisive in determining the substrate specificity of distinct 4CL isoenzymes. The two conserved peptide motifs in 4CL amino acid sequences observed by computer assisted sequence alignments were the Box Ⅰ motif, SSGTTGLPKGV, and the Box Ⅱ motif, GEICIRG. Antisense techniques of 4CL gene has been successfully applied to regulate the biosynthesis of the lignin in model plants such as Arabidopsis thaliana, Nicotiana tabacum and woody plant such as Populus tremuloides,Populus tomentosa. The future researches of 4CL should be emphasized particularly on the following aspects. More 4CL genes of woody plants should be separated and characterized by more advanced techniques. The research on the improvement of lignin content of woody plants is expected especially. The crystallization system of the 4CL protein should be established and the structure of 4CL protein should be illuminated from atom scale so that the relation of the 4CL structure and function would be elucidated.

Key words: 4-coumarate:coenzyme A ligase, vascular plants