Kouwen Thijs R H M, van der Goot Annemieke, Dorenbos Ronald, Winter Theresa, Antelmann Haike, Plaisier Marie-Claire, Quax Wim J, van Dijl January Maarten, Dubois Jean-Yves F
Department of Medical Microbiology, University Medical Center Groningen and University of Groningen, Hanzeplein 1, PO Box 30001, 9700 RB Groningen, The Netherlands.
Mol Microbiol. 2007 May;64(4):984-99. doi: 10.1111/j.1365-2958.2007.05707.x.
Disulphide bond formation catalysed by thiol-disulphide oxidoreductases (TDORs) is a universally conserved mechanism for stabilizing extracytoplasmic proteins. In Escherichia coli, disulphide bond formation requires a concerted action of distinct TDORs in thiol oxidation and subsequent quinone reduction. TDOR function in other bacteria has remained largely unexplored. Here we focus on TDORs of low-GC Gram-positive bacteria, in particular DsbA of Staphylococcus aureus and BdbA-D of Bacillus subtilis. Phylogenetic analyses reveal that the homologues DsbA and BdbD cluster in distinct groups typical for Staphylococcus and Bacillus species respectively. To compare the function of these TDORs, DsbA was produced in various bdb mutants of B. subtilis. Next, we assessed the ability of DsbA to sustain different TDOR-dependent processes, including heterologous secretion of E. coli PhoA, competence development and bacteriocin (sublancin 168) production. The results show that DsbA can function in all three processes. While BdbD needs a quinone oxidoreductase for activity, DsbA activity appears to depend on redox-active medium components. Unexpectedly, both quinone oxidoreductases of B. subtilis are sufficient to sustain production of sublancin. Moreover, DsbA can functionally replace these quinone oxidoreductases in sublancin production. Taken together, our unprecedented findings imply that TDOR systems of low-GC Gram-positive bacteria have a modular composition.
硫醇-二硫键氧化还原酶（TDORs）催化的二硫键形成是稳定胞外蛋白的一种普遍保守机制。在大肠杆菌中，二硫键形成需要不同的TDORs在硫醇氧化及随后的醌还原过程中协同作用。其他细菌中TDOR的功能在很大程度上仍未被探索。在这里，我们聚焦于低GC革兰氏阳性菌的TDORs，特别是金黄色葡萄球菌的DsbA和枯草芽孢杆菌的BdbA-D。系统发育分析表明，同源物DsbA和BdbD分别聚集在葡萄球菌属和芽孢杆菌属典型的不同组中。为了比较这些TDORs的功能，在枯草芽孢杆菌的各种bdb突变体中表达了DsbA。接下来，我们评估了DsbA维持不同TDOR依赖过程的能力，包括大肠杆菌PhoA的异源分泌、感受态发育和细菌素（sub168）的产生。结果表明，DsbA可以在所有这三个过程中发挥作用。虽然BdbD的活性需要醌氧化还原酶，但DsbA的活性似乎取决于具有氧化还原活性的培养基成分。出乎意料的是，枯草芽孢杆菌的两种醌氧化还原酶都足以维持sub168的产生。此外，在sub168产生过程中，DsbA可以在功能上替代这些醌氧化还原酶。综上所述，我们前所未有的发现表明，低GC革兰氏阳性菌的TDOR系统具有模块化组成。
