Study on in vivo effects of bacterial histidine kinase inhibitor, Waldiomycin, in Bacillus subtilis and Staphylococcus aureus

The Journal of General and Applied Microbiology

Md. Fakhruzzaman³  Ryutaro Utsumi³  Hirokazu Kino³  Yoko Eguchi²  Yohei Yanagida³  Yoichi Inukai³  Masayuki Igarashi¹ 

[1] Institute of Microbial Chemistry (BIKAKEN);Department of Science and Technology on Food Safety, Faculty of Biology-Oriented Science and Technology, Kinki University;Department of Bioscience, Graduate School of Agriculture, Kinki University

关键词: angucycline antibiotics;    Bacillus subtilis;    Enterococcus faecalis;    histidine kinase inhibitor;    Staphylococcus aureus;    Streptococcus mutans;    two-component signal transduction systems;    WalK/WalR;   

DOI  :  10.2323/jgam.61.177

学科分类：微生物学和免疫学

来源: Applied Microbiology, Molecular and Cellulrar Biosciences Research Foundation

【 摘 要 】

Two-component signal transduction systems (TCSs) represent one of the primary means by which bacteria sense and respond to changes in their environment, both intra- and extracellular. The highly conserved WalK (histidine kinase)/WalR (response regulator) TCS is essential for cell wall metabolism of low G+C Gram-positive bacteria and acts as a master regulatory system in controlling and coordinating cell wall metabolism with cell division. Waldiomycin, a WalK inhibitor, has been discovered by screening metabolites from actinomycetes and belongs to the family of angucycline antibiotics. In the present study, we have shown that waldiomycin inhibited autophosphorylation of WalK histidine kinases in vitro from Bacillus subtilis, Staphylococcus aureus, Enterococcus faecalis, and Streptococcus mutans at half-maximal inhibitory concentrations of 10.2, 8.8, 9.2, and 25.8 μM, respectively. Quantitative RT-PCR studies of WalR regulon genes have suggested that waldiomycin repressed the WalK/WalR system in B. subtilis and S. aureus cells. Morphology of waldiomycin-treated S. aureus cells displayed increased aggregation instead of proper cellular dissemination. Furthermore, autolysis profiles of S. aureus cells revealed that waldiomycin-treated cells were highly resistant to Triton X-100- and lysostaphin-induced lysis. These phenotypes are consistent with those of cells starved for the WalK/WalR system, indicating that waldiomycin inhibited the autophosphorylation activity of WalK in cells. We have also confirmed that waldiomycin inhibits WalK autophosphorylation in vivo by actually observing the phosphorylated WalK ratio in cells using Phos-tag SDS-PAGE. The results of our current study strongly suggest that waldiomycin targets WalK histidine kinases and inhibits the WalR regulon genes expression, thereby affecting both cell wall metabolism and cell division.

【 授权许可】

Unknown