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Research for outer membrane remodeling in Salmonella enterica

肠沙门氏菌外膜重塑研究

基本信息

批准号：
18590091
负责人：
KAWASAKI Kiyoshi
金额：
$ 2.57万
依托单位：
Doshisha Women's College of Liberal Arts
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2006
资助国家：
日本
起止时间：
2006 至 2007
项目状态：
已结题

项目摘要

Salmonella enterica serovar Typhimurium modifies its lipopolysaccharide (LPS), including the lipid A portion, in response to changes in its environment including host tissues. The lipid A 3-O-deacylase PagL, the expression of which is promoted under the host-mimetic environment, exhibits latency in S. enterica ; deacylation of lipid A is not usually observed in vivo despite the expression of the outer membrane protein PagL. In contrast, PagL does not exhibit latency in S. enterica pmrA and pmrE mutants, both of which are deficient in the aminoarabinose-based modification of lipid A, indicating that aminoarabinose-modified LPS species were involved in the latency. In order to analyze the machinery for PagL's repression, we generated PagL mutants in which an amino acid residue located at four extracellular loops was replaced with alanine. Apparent lipid A 3-O-deacylation was observed in S. enterica expressing the several PagL mutants, but not in S. enterica expressing wild-type PagL, suggesting that the point mutations released PagL from the latency. In addition, the mutations did not affect lipid A 3-O-deacylase activity of PagL in a S. enterica pmrA mutant or in E. coli BL21(DE3). These results, taken together, indicate that specific amino acid residues located at extracellular loops of PagL are involved in the recognition of aminoarabinose-modified LPS. Furthermore, S enterica expressing the PagL mutants showed apparent growth arrest at 43℃ compared with S. enterica expressing wild-type PagL, indicating that the latency of PagL is important for bacterial growth.

鼠伤寒沙门氏菌改变其脂多糖（LPS），包括脂质A部分，以响应其环境（包括宿主组织）的变化。脂质A3-O-脱酰酶PagL在拟宿主环境下表达增强，在S.肠;尽管外膜蛋白PagL的表达，脂质A的脱酰化通常在体内观察不到。相比之下，PagL在S中不表现出延迟。肠道pmrA和pmrE突变体，这两者都是缺乏基于氨基阿拉伯糖的修饰的脂质A，表明氨基阿拉伯糖修饰的LPS种类参与潜伏期。为了分析PagL的阻遏机制，我们产生了PagL突变体，其中位于四个细胞外环的氨基酸残基被丙氨酸取代。在S.肠杆菌表达几种PagL突变体，但在S.肠杆菌表达野生型PagL，表明点突变从潜伏期释放PagL。此外，突变不影响S. enterica pmrA突变体或E. coli BL21（DE3）。这些结果，放在一起，表明特定的氨基酸残基位于胞外环的PagL参与氨基阿拉伯糖修饰的LPS的识别。此外，表达PagL突变体的肠链球菌与S.肠杆菌表达野生型PagL，表明PagL的潜伏期对于细菌生长是重要的。