title: Divergent members of a soybean (Glycine max L.) 4-coumarate:coenzyme A ligase gene family.
abstract: 4-Coumarate:CoA ligase (4CL) is involved in the formation of coenzyme A thioesters of hydroxycinnamic acids that are central substrates for subsequent condensation, reduction, and transfer reactions in the biosynthesis of plant phenylpropanoids. Previous studies of 4CL appear to suggest that many isoenzymes are functionally equivalent in supplying substrates to various subsequent branches of phenylpropanoid biosyntheses. In contrast, divergent members of a 4CL gene family were identified in soybean (Glycine max L.). We isolated three structurally and functionally distinct 4CL cDNAs encoding 4CL1, 4CL2, and 4CL3 and the gene Gm4CL3. A fourth cDNA encoding 4CL4 had high similarity with 4CL3. The recombinant proteins expressed in Escherichia coli possessed highly divergent catalytic efficiency with various hydroxycinnamic acids. Remarkably, one isoenzyme (4CL1) was able to convert sinapate; thus the first cDNA encoding a 4CL that accepts highly substituted cinnamic acids is available for further studies on branches of phenylpropanoid metabolism that probably lead to the precursors of lignin. Surprisingly, the activity levels of the four isoenzymes and steady-state levels of their transcripts were differently affected after elicitor treatment of soybean cell cultures with a beta-glucan elicitor of Phytophthora sojae, revealing the down-regulation of 4CL1 vs. up-regulation of 4CL3/4. A similar regulation of the transcript levels of the different 4CL isoforms was observed in soybean seedlings after infection with Phytophthora sojae zoospores. Thus, partitioning of cinnamic acid building units between phenylpropanoid branch pathways in soybean could be regulated at the level of catalytic specificity and the level of expression of the 4CL isoenzymes.
authors.affiliation: Botanisches Institut der Universität, München, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Lindermayr
authors.forename: Britta
authors.initials: B
authors.lastname: Möllers
authors.forename: Judith
authors.initials: J
authors.lastname: Fliegmann
authors.forename: Annette
authors.initials: A
authors.lastname: Uhlmann
authors.forename: Friedrich
authors.initials: F
authors.lastname: Lottspeich
authors.forename: Harald
authors.initials: H
authors.lastname: Meimberg
authors.forename: Jürgen
authors.initials: J
authors.lastname: Ebel
mesh_terms: D003066:Coenzyme A Ligases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D003373:Coumaric Acids / Q000378:metabolism; D017343:Genes, Plant; D007527:Isoenzymes / Q000235:genetics; D008969:Molecular Sequence Data; D005810:Multigene Family; D011422:Propionates; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D013025:Glycine max / Q000201:enzymology / Q000235:genetics*; D014018:Tissue Distribution
chemical_list: D003373:Coumaric Acids; D007527:Isoenzymes; D011422:Propionates; D011994:Recombinant Proteins; C004999:ferulic acid; D003066:Coenzyme A Ligases; C019943:4-coumarate-CoA ligase; C495469:p-coumaric acid