首页 | 本学科首页   官方微博 | 高级检索  
   检索      


Functional and structural analysis of the siderophore synthetase AsbB through reconstitution of the petrobactin biosynthetic pathway from Bacillus anthracis
Authors:Nusca Tyler D  Kim Youngchang  Maltseva Natalia  Lee Jung Yeop  Eschenfeldt William  Stols Lucy  Schofield Michael M  Scaglione Jamie B  Dixon Shandee D  Oves-Costales Daniel  Challis Gregory L  Hanna Philip C  Pfleger Brian F  Joachimiak Andrzej  Sherman David H
Institution:Life Sciences Institute, University of Michigan Medical School, Ann Arbor, Michigan 48109, USA.
Abstract:Petrobactin, a mixed catechol-carboxylate siderophore, is required for full virulence of Bacillus anthracis, the causative agent of anthrax. The asbABCDEF operon encodes the biosynthetic machinery for this secondary metabolite. Here, we show that the function of five gene products encoded by the asb operon is necessary and sufficient for conversion of endogenous precursors to petrobactin using an in vitro system. In this pathway, the siderophore synthetase AsbB catalyzes formation of amide bonds crucial for petrobactin assembly through use of biosynthetic intermediates, as opposed to primary metabolites, as carboxylate donors. In solving the crystal structure of the B. anthracis siderophore biosynthesis protein B (AsbB), we disclose a three-dimensional model of a nonribosomal peptide synthetase-independent siderophore (NIS) synthetase. Structural characteristics provide new insight into how this bifunctional condensing enzyme can bind and adenylate multiple citrate-containing substrates followed by incorporation of both natural and unnatural polyamine nucleophiles. This activity enables formation of multiple end-stage products leading to final assembly of petrobactin. Subsequent enzymatic assays with the nonribosomal peptide synthetase-like AsbC, AsbD, and AsbE polypeptides show that the alternative products of AsbB are further converted to petrobactin, verifying previously proposed convergent routes to formation of this siderophore. These studies identify potential therapeutic targets to halt deadly infections caused by B. anthracis and other pathogenic bacteria and suggest new avenues for the chemoenzymatic synthesis of novel compounds.
Keywords:Bacillus  Crystal Structure  Iron Metabolism  Secondary Metabolism  Siderophores  Bacillus anthracis  Iron Acquisition  Petrobactin  Synthetase Structure
本文献已被 PubMed 等数据库收录!
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号