Document Detail


Characterisation of a prokaryote-type tRNA-isopentenyltransferase gene from the moss Physcomitrella patens.
MedLine Citation:
PMID:  17450376     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Cytokinins are of critical importance to numerous developmental processes in plants. Two cytokinin biosynthetic pathways have been described; each one uses a different type of isopentenyltransferases (IPTs) as the key enzyme. In the first pathway, adenylate-IPTs (EC 2.5.1.27) prenylate adenylic nucleotides to cytokinin nucleotides, thus catalysing the direct de novo biosynthesis of free cytokinins. In the second pathway, tRNA-IPTs (EC 2.5.1.8) catalyse cytokinin formation by isopentenylation of tRNA, the degradation of which liberates cytokinin nucleotides. Seed plants have been shown to possess both forms of IPTs. Here, we report on the in-silico based identification and on the functional characterisation of an IPT encoding gene (PpIPT1) from the bryophyte Physcomitrella patens. Analysis of the PpIPT1 amino acid sequence revealed high similarities to tRNA-IPTs of other plants. No adenylate-IPT genes were found in the Physcomitrella sequenced transcriptome/genome. PpIPT1 functionally complemented a defective tRNA-IPT gene of Saccharomyces cerevisiae (ScMOD5) in the strain MT-8. Dephosphorylated tRNA hydrolysates from PpIPT1-transformed MT-8 showed cytokinin activity in a moss bioassay and the presence of isopentenyladenosine in HPLC analysis, in contrast to those prepared from untransformed MT-8. A comparison of pro- and eukaryotic homologues revealed two classes of tRNA-IPTs; PpIPT1 belongs to a prokaryotic type with predicted chloroplast targeting. RT-PCR experiments revealed a stronger expression in the cytokinin overproducing mutant oveST25, thus indicating the potential role of PpIPT1 for cytokinin biosynthesis in the evolutionary old land plant Physcomitrella.
Authors:
Natalya A Yevdakova; Klaus von Schwartzenberg
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2007-04-21
Journal Detail:
Title:  Planta     Volume:  226     ISSN:  0032-0935     ISO Abbreviation:  Planta     Publication Date:  2007 Aug 
Date Detail:
Created Date:  2007-07-09     Completed Date:  2007-10-19     Revised Date:  2012-06-01    
Medline Journal Info:
Nlm Unique ID:  1250576     Medline TA:  Planta     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  683-95     Citation Subset:  IM    
Affiliation:
Biocenter Klein Flottbek and Botanical Garden, University of Hamburg, Ohnhorst street 18, 22609 Hamburg, Germany.
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MeSH Terms
Descriptor/Qualifier:
Alkyl and Aryl Transferases / chemistry,  genetics*,  metabolism
Amino Acid Motifs
Amino Acid Sequence
Biological Assay
Bryopsida / enzymology*,  genetics
Chromatography, High Pressure Liquid
Computational Biology
Expressed Sequence Tags
Gene Expression Regulation, Plant
Genetic Complementation Test
Isopentenyladenosine / chemistry,  metabolism
Molecular Sequence Data
Mutation / genetics
Phylogeny
Prokaryotic Cells / enzymology*
RNA, Transfer / metabolism
Saccharomyces cerevisiae / cytology,  enzymology
Saccharomyces cerevisiae Proteins / metabolism
Sequence Homology, Nucleic Acid
Transcription, Genetic
Transformation, Genetic
Chemical
Reg. No./Substance:
0/Saccharomyces cerevisiae Proteins; 7724-76-7/Isopentenyladenosine; 9014-25-9/RNA, Transfer; EC 2.5.-/Alkyl and Aryl Transferases; EC 2.5.1.75/MOD5 protein, S cerevisiae; EC 2.5.1.75/tRNA isopentenyltransferase

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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