Investigation into the role of the serine protease HtrA in Yersinia pestispathogenesis

The HtrA stress response protein has been shown to play a role in the virul ence of a number of pathogens. For some organisms, htrA mutants are attenua ted in the animal model and can be used as live vaccines. A Yersinia pestis htrA orthologue was identified, cloned and sequenced, showing 86% and 87% similarity to Escherichia coli and Salmonella tryphimurium HtrAs. An isogen ic Y. pestis htrA mutant was constructed using a reverse genetics approach. In contrast to the wild-type strain: the mutant failed to grow at an eleva ted temperature of 39 degrees C, but showed only a small increase in sensit ivity to oxidative stress and was only partially attenuated in the animal m odel. However, the mutant exhibited a different protein expression profile to that of the wild-type strain when grown at 28 degrees C to simulate grow th in the flea. (C) 2000 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.