This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Cohn, M. T. Articles by Brøndsted, L. Search for Related Content PubMed PubMed Citation Articles by Cohn, M. T. Articles by Brøndsted, L. Agricola Articles by Cohn, M. T. Articles by Brøndsted, L.

Next Article 

Applied and Environmental Microbiology, December 2007, p. 7803-7813, Vol. 73, No. 24
0099-2240/07/$08.00+0     doi:10.1128/AEM.00698-07
Copyright © 2007, American Society for Microbiology. All Rights Reserved.

Contribution of Conserved ATP-Dependent Proteases of Campylobacter jejuni to Stress Tolerance and Virulence

Marianne Thorup Cohn,¹ Hanne Ingmer,¹ Francis Mulholland,² Kirsten Jørgensen,¹ Jerry M. Wells,^2, and Lone Brøndsted^1*

Department of Veterinary Pathobiology, Faculty of Life Sciences, Stigbøjlen 4, DK-1870 Frederiksberg C, Denmark,¹ Institute of Food Research, Norwich Research Park, Colney, Norwich NR4 7UA, United Kingdom²

Received 28 March 2007/ Accepted 5 October 2007

In prokaryotic cells the ATP-dependent proteases Lon and ClpP (Clp proteolytic subunit) are involved in the turnover of misfolded proteins and the degradation of regulatory proteins, and depending on the organism, these proteases contribute variably to stress tolerance. We constructed mutants in the lon and clpP genes of the food-borne human pathogen Campylobacter jejuni and found that the growth of both mutants was impaired at high temperature, a condition known to increase the level of misfolded protein. Moreover, the amounts of misfolded protein aggregates were increased when both proteases were absent, and we propose that both ClpP and Lon are involved in eliminating misfolded proteins in C. jejuni. In order to bind misfolded protein, ClpP has to associate with one of several Clp ATPases. Following inactivation of the ATPase genes clpA and clpX, only the clpX mutant displayed the same heat sensitivity as the clpP mutant, indicating that the ClpXP proteolytic complex is responsible for the degradation of heat-damaged proteins in C. jejuni. Notably, ClpP and ClpX are required for growth at 42°C, which is the temperature of the intestinal tract of poultry, one of the primary carriers of C. jejuni. Thus, ClpP and ClpX may be suitable targets of new intervention strategies aimed at reducing C. jejuni in poultry production. Further characterization of the clpP and lon mutants revealed other altered phenotypes, such as reduced motility, less autoagglutination, and lower levels of invasion of INT407 epithelial cells, suggesting that the proteases may contribute to the virulence of C. jejuni.

---

* Corresponding author. Mailing address: Department of Veterinary Pathobiology, Faculty of Life Sciences, Stigbøjlen 4, DK-1870 Frederiksberg C, Denmark. Phone: 45 35 33 27 64. Fax: 45 35 33 27 57. E-mail: lobr{at}life.ku.dk

Published ahead of print on 12 October 2007.

Present address: Department of Animal Sciences, Wageningen University, Marijkeweg 40, 6709 PG Wageningen, The Netherlands.

---

Applied and Environmental Microbiology, December 2007, p. 7803-7813, Vol. 73, No. 24
0099-2240/07/$08.00+0     doi:10.1128/AEM.00698-07
Copyright © 2007, American Society for Microbiology. All Rights Reserved.

This article has been cited by other articles:

• de Bruijn, I., Raaijmakers, J. M. (2009). Regulation of Cyclic Lipopeptide Biosynthesis in Pseudomonas fluorescens by the ClpP Protease. J. Bacteriol. 191: 1910-1923 [Abstract] [Full Text]  
• Gonzalez, M., Hakkinen, M., Rautelin, H., Hanninen, M.-L. (2009). Bovine Campylobacter jejuni Strains Differ from Human and Chicken Strains in an Analysis of Certain Molecular Genetic Markers. Appl. Environ. Microbiol. 75: 1208-1210 [Abstract] [Full Text]