文章基本信息

标题：Structure Function Analysis of Novel Type III Polyketide Synthases from Arabidopsis thaliana
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作者：Yuusuke Mizuuchi ; Yoshihiko Shimokawa ; Kiyofumi Wanibuchi 等
期刊名称：Biological and Pharmaceutical Bulletin
印刷版ISSN：0918-6158
电子版ISSN：1347-5215
出版年度：2008
卷号：31
期号：12
页码：2205-2210
DOI：10.1248/bpb.31.2205
出版社：The Pharmaceutical Society of Japan
摘要：The genome sequencing project revealed presence of two active chalcone synthase (CHS) homologues ( At1g02050 and At4g34850 ) in the model plant Arabidopsis thaliana . We report herein the two genes encode closely related novel plant-specific type III polyketide synthases (PKSs) that produces long-chain alkyl α-pyrones. PKS-A ( At1g02050 ) and PKS-B ( At4g34850 ) share significantly low amino acid sequence identity (20—40%) with other type III PKSs, and the phylogenetic tree analysis revealed that they form a separate cluster located closely to those of bacterial type III PKSs. When expressed in Escherichia coli , both PKS-A and PKS-B accepted unusually long (up to the C₂₀ chain-length) fatty acyl CoAs as a starter substrate, and carried out sequential condensations with malonyl-CoA to produce triketide and tetraketide α-pyrones. Interestingly, despite the low sequence identity, homology modeling revealed that the active-site architecture of PKS-A and PKS-B showed similarity to that of a bacterial type III PKS from Mycobacterium tuberculosis .
关键词：Arabidopsis thaliana;type III polyketide synthase;chalcone synthase;long-chain α-pyrone;pyrone lipid;homology modeling