The vbs genes that direct synthesis of the siderophore vicibactin in Rhizobium leguminosarum:: their expression in other genera requires ECF σ factor Rpol
The vbs genes that direct synthesis of the siderophore vicibactin in Rhizobium leguminosarum:: their expression in other genera requires ECF σ factor Rpol
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DOI：
10.1046/j.1365-2958.2002.02951.x
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发表时间：
2002-06-01
影响因子：
3.6
通讯作者：
Yeoman, KH
中科院分区：
文献类型：
--
作者：
Carter, RA;Worsley, PS;Yeoman, KH
一组八个基因，vbsGSO，vbsADL，vbsC和vbsP，参与合成vicibactin，一个环状的，三异羟肟酸铁载体由共生细菌根瘤菌豆科。豌豆或蚕豆上共生N-2固定不需要这些vbs基因。转录的vbsC，vbsGSO和vbsADL（但不是vbsP）的增长，在低水平的铁。vbsGSO和vbsADL的转录，而不是vbsP或vbsC，需要紧密连锁的基因rpoI，它编码RNA聚合酶的ECF σ因子。将克隆的vbs基因加上rpoI转移到红细菌属、副球菌属和中华根瘤菌属中，使这些其他属具有生产vicibactin的能力。我们提出了一个vibactin合成的生化遗传模型，该模型包含了不同vbs突变体的表型和vbs基因产物的同源性。在这个模型中，VbsS，这是类似于许多非核糖体肽合成酶多酶，具有核心作用。提出VbsS通过作为酰基硫酯共价连接至肽基载体蛋白结构域来活化L-N（5）-羟基鸟氨酸。随后的VbsA催化的羟基鸟氨酸的酰化，接着是VbsL介导的差向异构化和VbsC催化的乙酰化，产生vicibactin亚基，其然后被VbsS的硫酯酶结构域三聚化和环化以得到完整的铁载体。
A cluster of eight genes, vbsGSO , vbsADL , vbsC and vbsP , are involved in the synthesis of vicibactin, a cyclic, trihydroxamate siderophore made by the symbiotic bacterium Rhizobium leguminosarum . None of these vbs genes was required for symbiotic N-2 fixation on peas or Vicia . Transcription of vbsC , vbsGSO and vbsADL (but not vbsP ) was enhanced by growth in low levels of Fe. Transcription of vbsGSO and vbsADL , but not vbsP or vbsC , required the closely linked gene rpoI , which encodes an ECF sigma factor of RNA polymerase. Transfer of the cloned vbs genes, plus rpoI , to Rhodobacter , Paracoccus and Sinorhizobium conferred the ability to make vicibactin on these other genera. We present a biochemical genetic model of vicibactin synthesis, which accommodates the phenotypes of different vbs mutants and the homologies of the vbs gene products. In this model, VbsS, which is similar to many non-ribosomal peptide synthetase multienzymes, has a central role. It is proposed that VbsS activates L-N (5) -hydroxyornithine via covalent attachment as an acyl thioester to a peptidyl carrier protein domain. Subsequent VbsA-catalysed acylation of the hydroxyornithine, followed by VbsL-mediated epimerization and acetylation catalysed by VbsC, yields the vicibactin subunit, which is then trimerized and cyclized by the thioesterase domain of VbsS to give the completed siderophore.