Role of BacA in Lipopolysaccharide Synthesis, Peptide Transport, and Nodulation by Rhizobium sp Strain NGR234
Role of BacA in Lipopolysaccharide Synthesis, Peptide Transport, and Nodulation by Rhizobium sp Strain NGR234
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DOI：
10.1128/jb.01260-10
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发表时间：
2011-05-01
影响因子：
3.2
通讯作者：
Deakin, William J.
中科院分区：
文献类型：
--
作者：
Ardissone, Silvia;Kobayashi, Hajime;Deakin, William J.
苜蓿中华根瘤菌（Sinorhizobium meliloti）的巴卡A（BacA）在苜蓿固氮共生体系的建立中起着重要作用，它参与了肽的输入和将超长链脂肪酸（VLCFA）添加到脂多糖（LPS）的脂质A中。我们通过突变巴卡A基因来研究巴卡A在根瘤菌菌株NGR 234中的作用。在NGR 234巴卡A突变体中，肽输入受损，但未观察到对VLCFA添加的影响。更重要的是，突变体的共生能力与野生型的各种豆类物种。同时，产生并测定NGR 234的acpXL突变体。在根瘤菌中，AcpXL是将VLCFA添加到脂质A所必需的专用酰基载体蛋白。从NGR 234突变体中提取的LPS缺乏VLCFA，并且该突变体与大多数测试的豆类形成功能性结节的能力严重受损。我们的工作证明了VLCFA在NGR 234-豆科植物共生中的重要性，也表明巴卡A对类杆菌分化的必要性仅限于特定的豆科植物-根瘤菌相互作用。
BacA of Sinorhizobium meliloti plays an essential role in the establishment of nitrogen-fixing symbioses with Medicago plants, where it is involved in peptide import and in the addition of very-long-chain fatty acids (VLCFA) to lipid A of lipopolysaccharide (LPS). We investigated the role of BacA in Rhizobium species strain NGR234 by mutating the bacA gene. In the NGR234 bacA mutant, peptide import was impaired, but no effect on VLCFA addition was observed. More importantly, the symbiotic ability of the mutant was comparable to that of the wild type for a variety of legume species. Concurrently, an acpXL mutant of NGR234 was created and assayed. In rhizobia, AcpXL is a dedicated acyl carrier protein necessary for the addition of VLCFA to lipid A. LPS extracted from the NGR234 mutant lacked VLCFA, and this mutant was severely impaired in the ability to form functional nodules with the majority of legumes tested. Our work demonstrates the importance of VLCFA in the NGR234-legume symbiosis and also shows that the necessity of BacA for bacteroid differentiation is restricted to specific legume-Rhizobium interactions.