title: A maize cytokinin gene encoding an O-glucosyltransferase specific to cis-zeatin.
abstract: Zeatin is a naturally occurring cytokinin. Biosynthesis and metabolism studies of zeatin have been directed mostly at the trans isomer, although cis-zeatin and its riboside occur as major components in some plant species. It is not known whether parallel regulatory pathways exist for the two isomers. Based on the sequence of the gene ZOG1 encoding a trans-zeatin O-glucosyltransferase from Phaseolus (EC ), a cis-zeatin-specific O-glucosyltransferase was isolated from maize. This gene, cisZOG1, contains an ORF of 1,401 nucleotides encoding a protein of 51.1 kDa with 41% identity to the Phaseolus ZOG1 protein. Unexpectedly, the maize enzyme recognizes as substrates cis-zeatin and UDP-glucose but not cis-ribosylzeatin, trans-zeatin, or trans-ribosylzeatin. This finding indicates the existence of cis-specific regulatory elements in plants and suggests that cis-zeatin and derivatives may be more important in cytokinin homeostasis than currently recognized.
authors.affiliation: Department of Horticulture and Center for Gene Research and Biotechnology, Oregon State University, Corvallis, OR 97331-7304, USA.
authors.forename: R C
authors.initials: RC
authors.lastname: Martin
authors.forename: M C
authors.initials: MC
authors.lastname: Mok
authors.forename: J E
authors.initials: JE
authors.lastname: Habben
authors.forename: D W
authors.initials: DW
authors.lastname: Mok
mesh_terms: D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D003583:Cytokinins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D018076:DNA, Complementary; D020224:Expressed Sequence Tags; D005964:Glucosyltransferases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D010940:Plant Proteins; D012333:RNA, Messenger / Q000235:genetics; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity; D003313:Zea mays / Q000235:genetics*; D015026:Zeatin / Q000378:metabolism*
chemical_list: D003583:Cytokinins; D018076:DNA, Complementary; D010940:Plant Proteins; D012333:RNA, Messenger; D011994:Recombinant Proteins; D015026:Zeatin; D005964:Glucosyltransferases; C117387:UDPglucose zeatin O-glucosyltransferase, plant