Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, FE28017177, Stockholm, Sweden.
J Bacteriol. 2011 Dec;193(23):6443-51. doi: 10.1128/JB.00425-11. Epub 2011 Sep 30.
In Salmonella enterica serovar Typhimurium, a biofilm mode of growth known as the rdar morphotype is regulated by several networks which sense multiple environmental signals. The transcriptional regulator CsgD is the major target for these regulatory pathways. In this study, we show that two lytic transglycosylases of family I, MltE and MltC, in combination increase CsgD expression and rdar morphotype. MltE and MltC, which share a highly similar transglycosylase SLT domain, work redundantly to regulate CsgD at the transcriptional and posttranscriptional levels. The effect of MltE and MltC on CsgD levels was independent of the known regulatory pathways that sense cell envelope stress. These findings reveal, for the first time, a specific function of lytic transglycosylases in S. Typhimurium and suggest the existence of a new signaling pathway that links cell wall turnover to biofilm formation.
在鼠伤寒沙门氏菌中，一种被称为 rdar 形态的生物膜生长模式受到多个网络的调控，这些网络可以感知多种环境信号。转录调节因子 CsgD 是这些调节途径的主要靶标。在这项研究中，我们表明，家族 I 的两种溶菌转糖苷酶 MltE 和 MltC 联合起来可以增加 CsgD 的表达和 rdar 形态。MltE 和 MltC 具有高度相似的转糖苷酶 SLT 结构域，在转录和转录后水平上冗余地调节 CsgD。MltE 和 MltC 对 CsgD 水平的影响不依赖于感知细胞 envelope stress 的已知调节途径。这些发现首次揭示了溶菌转糖苷酶在鼠伤寒沙门氏菌中的特定功能，并表明存在一种将细胞壁周转与生物膜形成联系起来的新信号通路。
