Section of Molecular Microbiology, Department of Molecular Cell Biology, VU University, Amsterdam, The Netherlands.
J Bacteriol. 2013 Feb;195(4):788-97. doi: 10.1128/JB.01355-12. Epub 2012 Dec 7.
The two-partner secretion (TPS) systems of Gram-negative bacteria consist of a large secreted exoprotein (TpsA) and a transporter protein (TpsB) located in the outer membrane. TpsA targets TpsB for transport across the membrane via its ∼30-kDa TPS domain located at its N terminus, and this domain is also the minimal secretory unit. Neisseria meningitidis genomes encode up to five TpsAs and two TpsBs. Sequence alignments of TPS domains suggested that these are organized into three systems, while there are two TpsBs, which raised questions on their system specificity. We show here that the TpsB2 transporter of Neisseria meningitidis is able to secrete all types of TPS domains encoded in N. meningitidis and the related species Neisseria lactamica but not domains of Haemophilus influenzae and Pseudomonas aeruginosa. In contrast, the TpsB1 transporter seemed to be specific for its cognate N. meningitidis system and did not secrete the TPS domains of other meningococcal systems. However, TpsB1 did secrete the TPS2b domain of N. lactamica, which is related to the meningococcal TPS2 domains. Apparently, the secretion depends on specific sequences within the TPS domain rather than the overall TPS domain structure.
革兰氏阴性菌的双组分分泌（TPS）系统由一个大型分泌外蛋白（TpsA）和一个位于外膜中的转运蛋白（TpsB）组成。TpsA 通过其位于 N 端的约 30 kDa 的 TPS 结构域靶向 TpsB 进行跨膜运输，该结构域也是最小的分泌单位。脑膜炎奈瑟菌基因组编码多达 5 种 TpsA 和 2 种 TpsB。TPS 结构域的序列比对表明，这些结构域分为三个系统，而有两种 TpsB，这就引发了它们系统特异性的问题。我们在这里表明，脑膜炎奈瑟菌的 TpsB2 转运蛋白能够分泌脑膜炎奈瑟菌和相关物种淋病奈瑟菌编码的所有类型的 TPS 结构域，但不能分泌流感嗜血杆菌和铜绿假单胞菌的结构域。相比之下，TpsB1 转运蛋白似乎对其同源的脑膜炎奈瑟菌系统具有特异性，不能分泌其他脑膜炎球菌系统的 TPS 结构域。然而，TpsB1 确实分泌了与脑膜炎球菌 TPS2 结构域相关的淋病奈瑟菌 TPS2b 结构域。显然，分泌依赖于 TPS 结构域内的特定序列，而不是 TPS 结构域的整体结构。
