The cell envelope-associated protein, LytR, regulates the cysteine protease SpeB in Streptococcus pyogenes

Department of Bacteriology, Nagoya City University Graduate School of Medical Sciences, Japan.
Apmis (Impact Factor: 2.04). 05/2012; 120(5):417-26. DOI: 10.1111/j.1600-0463.2011.02847.x
Source: PubMed


Minami M, Ichikawa M, Ohta M, Hasegawa T. The cell envelope-associated protein, LytR, regulates the cysteine protease SpeB in Streptococcus pyogenes. APMIS 2012; 120: 417–26.
The LytR family of cell envelope-associated transcriptional attenuators in bacteria has been brought into focus of scientific interest on the expression of various virulence factors, as well as bacterial cell envelope maintenance. However, this protein of Streptococcus pyogenes has been only described as cell surface-associated protein, and its function is completely unknown. We created lytR mutant strains from two independent S. pyogenes strains to analyze the function of LytR. The protease assay in culture supernatant showed that lytR mutant had the higher cysteine protease activity than wild-type. Two-dimensional gel electrophoresis and western blotting analysis revealed that the amount of cysteine protease, SpeB in lytR mutant was more compared with that in wild-type. The level of speB mRNA in lytR mutant also increased compared with that of wild-type. The membrane integrity and potential in lytR mutant also were decreased compared with that of wild-type. Murine infection model showed that less survival was detected in mice inoculated with lytR mutant than that with wild-type, and the size of wound lesion of mice with lytR mutant was larger than that with wild-type. Our data suggest that the lytR regulates the expression of SpeB in S. pyogenes with relation to membrane integrity.

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    • "Although the main function of these proteins remains unclear, they are known to influence the clinically relevant attributes of various gram-positive pathogens, such as cell division and septum formation (Chatfield et al., 2005; Hübscher et al., 2008; Johnsborg and Havarstein, 2009; Over et al., 2011). Recently, Minami et al. (2012) found that the lytR mutant strain of the gram-positive bacterium Streptococcus pyogenes had a higher activity of the cysteine protease SpeB and was more virulent than the wild-type strain. Consistent with the results of Dumas et al. (2008), the LytR protein of S. pyogenes (25% similar to the Lmo0443 protein of L. monocytogenes) seems to play an important role in the virulence of S. pyogenes. "
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