Dubrac Sarah, Bisicchia Paola, Devine Kevin M, Msadek Tarek
Biology of Gram-Positive Pathogens, CNRS URA 2172, Department of Microbiology, Institut Pasteur, 25, Rue du Dr Roux, 75724 Paris Cedex 15, France.
Mol Microbiol. 2008 Dec;70(6):1307-22. doi: 10.1111/j.1365-2958.2008.06483.x. Epub 2008 Oct 23.
The WalK/WalR (aka YycG/YycF) two-component system (TCS), originally identified in Bacillus subtilis, is very highly conserved and specific to low G+C Gram-positive bacteria, including a number of important pathogens. An unusual feature is that this system is essential for viability in most of these bacteria. Recent studies have revealed conserved functions for this system, defining this signal transduction pathway as a crucial regulatory system for cell wall metabolism, that we have accordingly renamed WalK/WalR. Here we review the cellular role of the WalK/WalR TCS in different bacterial species, focusing on the function of genes in its regulon, as well as variations in walRK operon structure and the composition of its regulon. We also discuss the nature of its essentiality and the potential type of signal being sensed. The WalK histidine kinase of B. subtilis has been shown to localize to the divisome and we suggest that the WalKR system acts as an information conduit between extracytoplasmic cellular structures and intracellular processes required for their synthesis, playing a vital role in effectively co-ordinating peptidoglycan plasticity with the cell division process.
WalK/WalR（又称YycG/YycF）双组分系统（TCS）最初是在枯草芽孢杆菌中发现的，它在低G+C革兰氏阳性菌中高度保守且具有特异性，其中包括许多重要的病原体。一个不同寻常的特点是，该系统对于大多数这类细菌的生存至关重要。最近的研究揭示了该系统的保守功能，将这个信号转导途径定义为细胞壁代谢的关键调控系统，因此我们将其重新命名为WalK/WalR。在这里，我们综述了WalK/WalR双组分系统在不同细菌物种中的细胞作用，重点关注其调控子中基因的功能，以及walRK操纵子结构及其调控子组成的变化。我们还讨论了其必需性的本质以及所感知信号的潜在类型。枯草芽孢杆菌的WalK组氨酸激酶已被证明定位于分裂体，我们认为WalKR系统充当细胞外结构与它们合成所需的细胞内过程之间的信息通道，在有效协调肽聚糖可塑性与细胞分裂过程中发挥着至关重要的作用。
