Saak Christina C, Zepeda-Rivera Martha A, Gibbs Karine A
Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts, United States of America.
PLoS One. 2017 Sep 26;12(9):e0184797. doi: 10.1371/journal.pone.0184797. eCollection 2017.
The type VI secretion (T6S) system is a molecular device for the delivery of proteins from one cell into another. T6S function depends on the contractile sheath comprised of TssB/VipA and TssC/VipB proteins. We previously reported on a mutant variant of TssB that disrupts T6S-dependent export of the self-identity protein, IdsD, in the bacterium Proteus mirabilis. Here we determined the mechanism underlying that initial observation. We show that T6S-dependent export of multiple self-recognition proteins is abrogated in this mutant strain. We have mapped the mutation, which is a single amino acid change, to a region predicted to be involved in the formation of the TssB-TssC sheath. We have demonstrated that this mutation does indeed inhibit sheath formation, thereby explaining the global disruption of T6S activity. We propose that this mutation could be utilized as an important tool for studying functions and behaviors associated with T6S systems.
VI型分泌（T6S）系统是一种用于将蛋白质从一个细胞传递到另一个细胞的分子装置。T6S的功能取决于由TssB/VipA和TssC/VipB蛋白组成的收缩鞘。我们之前报道了TssB的一个突变变体，它破坏了奇异变形杆菌中自我识别蛋白IdsD的T6S依赖性输出。在此，我们确定了该初步观察结果背后的机制。我们表明，在该突变菌株中，多种自我识别蛋白的T6S依赖性输出被消除。我们已将该突变（一个单氨基酸变化）定位到预测参与TssB - TssC鞘形成的区域。我们已证明该突变确实抑制鞘的形成，从而解释了T6S活性的整体破坏。我们提出，该突变可作为研究与T6S系统相关的功能和行为的重要工具。
