title: Functional characterization of evolutionarily divergent 4-coumarate:coenzyme a ligases in rice.
abstract: 4-Coumarate:coenzyme A ligase (4CL; EC 6.2.1.12) is a key enzyme in the phenylpropanoid metabolic pathways for monolignol and flavonoid biosynthesis. 4CL has been much studied in dicotyledons, but its function is not completely understood in monocotyledons, which display a different monolignol composition and phenylpropanoid profile. In this study, five members of the 4CL gene family in the rice (Oryza sativa) genome were cloned and analyzed. Biochemical characterization of the 4CL recombinant proteins revealed that the rice 4CL isoforms displayed different substrate specificities and catalytic turnover rates. Among them, Os4CL3 exhibited the highest turnover rate. No apparent tissue-specific expression of the five 4CLs was observed, but significant differences in their expression levels were detected. The rank in order of transcript abundance was Os4CL3 > Os4CL5 > Os4CL1 > Os4CL4 > Os4CL2. Suppression of Os4CL3 expression resulted in significant lignin reduction, shorter plant growth, and other morphological changes. The 4CL-suppressed transgenics also displayed decreased panicle fertility, which may be attributed to abnormal anther development as a result of disrupted lignin synthesis. This study demonstrates that the rice 4CLs exhibit different in vitro catalytic properties from those in dicots and that 4CL-mediated metabolism in vivo may play important roles in regulating a broad range of biological events over the course of rice growth and development.
authors.affiliation: Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China.
authors.forename: Jinshan
authors.initials: J
authors.lastname: Gui
authors.forename: Junhui
authors.initials: J
authors.lastname: Shen
authors.forename: Laigeng
authors.initials: L
authors.lastname: Li
mesh_terms: D005075:Biological Evolution; D003001:Cloning, Molecular; D003066:Coenzyme A Ligases / Q000235:genetics* / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D008031:Lignin / Q000378:metabolism; D005810:Multigene Family; D012275:Oryza / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D018515:Plant Leaves / Q000201:enzymology / Q000235:genetics; D030821:Plants, Genetically Modified; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D007527:Isoenzymes; D011994:Recombinant Proteins; D008031:Lignin; D003066:Coenzyme A Ligases; C019943:4-coumarate-CoA ligase