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A SABATH Methyltransferase from the moss Physcomitrella patens catalyzes S-methylation of thiols and has a role in detoxification.
MedLine Citation:
PMID:  22795762     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Known SABATH methyltransferases, all of which were identified from seed plants, catalyze methylation of either the carboxyl group of a variety of low molecular weight metabolites or the nitrogen moiety of precursors of caffeine. In this study, the SABATH family from the bryophyte Physcomitrella patens was identified and characterized. Four SABATH-like sequences (PpSABATH1, PpSABATH2, PpSABATH3, and PpSABATH4) were identified from the P. patens genome. Only PpSABATH1 and PpSABATH2 showed expression in the leafy gametophyte of P. patens. Full-length cDNAs of PpSABATH1 and PpSABATH2 were cloned and expressed in soluble form in Escherichia coli. Recombinant PpSABATH1 and PpSABATH2 were tested for methyltransferase activity with a total of 75 compounds. While showing no activity with carboxylic acids or nitrogen-containing compounds, PpSABATH1 displayed methyltransferase activity with a number of thiols. PpSABATH2 did not show activity with any of the compounds tested. Among the thiols analyzed, PpSABATH1 showed the highest level of activity with thiobenzoic acid with an apparent Km value of 95.5μM, which is comparable to those of known SABATHs. Using thiobenzoic acid as substrate, GC-MS analysis indicated that the methylation catalyzed by PpSABATH1 is on the sulfur atom. The mechanism for S-methylation of thiols catalyzed by PpSABATH1 was partially revealed by homology-based structural modeling. The expression of PpSABATH1 was induced by the treatment of thiobenzoic acid. Further transgenic studies showed that tobacco plants overexpressing PpSABATH1 exhibited enhanced tolerance to thiobenzoic acid, suggesting that PpSABATH1 have a role in the detoxification of xenobiotic thiols.
Authors:
Nan Zhao; Jean-Luc Ferrer; Hong S Moon; Jeremy Kapteyn; Xiaofeng Zhuang; Mitsuyasu Hasebe; C Neal Stewart; David R Gang; Feng Chen
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-7-12
Journal Detail:
Title:  Phytochemistry     Volume:  -     ISSN:  1873-3700     ISO Abbreviation:  -     Publication Date:  2012 Jul 
Date Detail:
Created Date:  2012-7-16     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0151434     Medline TA:  Phytochemistry     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
Copyright © 2012 Elsevier Ltd. All rights reserved.
Affiliation:
Department of Plant Sciences, University of Tennessee, Knoxville, TN 37996, USA.
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