A tamB homolog is involved in maintenance of cell envelope integrity and stress resistance of Deinococcus radiodurans.
A tamB homolog is involved in maintenance of cell envelope integrity and stress resistance of Deinococcus radiodurans.
复制标题
tamB 同源物参与耐辐射奇球菌细胞包膜完整性和应激抵抗力的维持
DOI：
10.1038/srep45929
复制
发表时间：
2017-04-06
影响因子：
4.6
通讯作者：
Tian B
中科院分区：
文献类型：
--
作者：
Yu J;Li T;Dai S;Weng Y;Li J;Li Q;Xu H;Hua Y;Tian B
细菌的易位和组装模块（TAM）由TamA和TamB组成，它们形成一个复合物来控制外膜蛋白的运输和分泌。本研究表明，耐辐射球菌1号染色体上缺乏tamA同源物的DR_1462-DR_1461-DR_1460基因位点是一个tamB同源物（DR_146T），具有两个tamB基序和一个DUF490基序。DR_146T突变导致细胞包膜剥离，抗剪切和渗透压能力下降，抗氧化应激能力增强，这与表面s层蛋白SlpA （DR_2577）突变体的表型一致，表明DR_146T参与维持细胞包膜完整性。DR_146T突变体的细胞包膜中不存在123 kDa的SlpA，只有其片段存在，表明DR_146T可能参与了s层的维持。缺少DUF490基序的突变体在表型上与野生型相比只有轻微的改变，这表明DUF490基序对DR_146T功能的作用不如tamB基序重要。这些发现增强了我们对极端嗜冷D. radiodurans多层包膜特性的理解，以及细菌中tam的多样性和功能。
The translocation and assembly module (TAM) in bacteria consists of TamA and TamB that form a complex to control the transport and secretion of outer membrane proteins. Herein, we demonstrated that the DR_1462-DR_1461-DR_1460 gene loci on chromosome 1 of Deinococcus radiodurans, which lacks tamA homologs, is a tamB homolog (DR_146T) with two tamB motifs and a DUF490 motif. Mutation of DR_146T resulted in cell envelope peeling and a decrease in resistance to shear stress and osmotic pressure, as well as an increase in oxidative stress resistance, consistent with the phenotype of a surface layer (S-layer) protein SlpA (DR_2577) mutant, demonstrating the involvement of DR_146T in maintenance of cell envelope integrity. The 123 kDa SlpA was absent and only its fragments were present in the cell envelope of DR_146T mutant, suggesting that DR_146T might be involved in maintenance of the S-layer. A mutant lacking the DUF490 motif displayed only a slight alteration in phenotype compared with the wild type, suggesting DUF490 is less important than tamB motif for the function of DR_146T. These findings enhance our understanding of the properties of the multilayered envelope in extremophilic D. radiodurans, as well as the diversity and functions of TAMs in bacteria.