Kwan Daniel C, Thomas Judith R, Bolhuis Albert
Department of Pharmacy and Pharmacology, University of Bath, UK.
FEBS J. 2008 Dec;275(24):6159-67. doi: 10.1111/j.1742-4658.2008.06740.x. Epub 2008 Nov 5.
Twin-arginine translocase (Tat) is involved in the translocation of fully folded proteins in a process that is driven by the proton motive force. In most prokaryotes, the Tat system transports only a small proportion of secretory proteins, and Tat substrates are often cofactor-containing proteins that require folding before translocation. A notable exception is found in halophilic archaea (haloarchaea), which are predicted to secrete the majority of their proteins through the Tat pathway. In this study, we have analysed the translocation of a secretory protein (AmyH) from the haloarchaeon Haloarcula hispanica. Using both in vivo and in vitro translocation assays, we demonstrate that AmyH transport is Tat-dependent, and, surprisingly, that its secretion does not depend on the proton motive force but requires the sodium motive force instead.
双精氨酸转位酶（Tat）参与由质子动力驱动的完全折叠蛋白的转位过程。在大多数原核生物中，Tat系统仅转运一小部分分泌蛋白，Tat底物通常是含辅因子的蛋白，在转位前需要折叠。嗜盐古菌（嗜盐古生菌）是一个显著的例外，预计它们的大多数蛋白通过Tat途径分泌。在本研究中，我们分析了嗜盐古菌西班牙嗜盐嗜盐菌分泌蛋白（AmyH）的转位。通过体内和体外转位试验，我们证明AmyH的转运依赖于Tat，而且令人惊讶的是，其分泌不依赖于质子动力，而是需要钠动力。
