Biosynthesis of cytokinins.
Cytokinins are adenine derivatives with an isoprenoid side chain and play an essential role in plant development. Plant isopentenyltransferases that catalyze the first and rate-limiting steps of cytokinin biosynthesis have recently been identified. Unlike bacterial enzymes, which catalyze the transfer of the isopentenyl moiety from dimethylallyldiphosphate (DMAPP) to the N(6) position of adenosine 5'-monophosphate (AMP), plant enzymes catalyze the transfer of the isopentenyl moiety from DMAPP preferentially to ATP and to ADP. The isopentenylated side chain is hydroxylated to form zeatin-type cytokinins. An alternative pathway, in which a hydroxylated side chain is directly added to the N(6) position of the adenine moiety, has also been suggested.
Kakimoto
Tatsuo
T
Department of Biology, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan. kakimoto@bio.sci.osaka-u.ac.jp
D019883:Alkyl and Aryl Transferases / Q000378:metabolism; D003583:Cytokinins / Q000096:biosynthesis* / Q000737:chemistry; D006900:Hydroxylation; D019684:Magnoliopsida / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D012343:RNA, Transfer / Q000378:metabolism
D003583:Cytokinins; D012343:RNA, Transfer; D019883:Alkyl and Aryl Transferases; C024274:adenylate isopentenyltransferase