Previous Article | Next Article ![]()
Journal of Bacteriology, November 2007, p. 8099-8108, Vol. 189, No. 22
0021-9193/07/$08.00+0 doi:10.1128/JB.01037-07
Copyright © 2007, American Society for Microbiology. All Rights Reserved.
,
University of British Columbia, Department of Microbiology and Immunology, Vancouver, British Columbia, Canada,1 Vaccine and Infectious Disease Organization, Saskatoon, Saskatchewan, Canada,2 Stanford University, Department of Biochemistry, Stanford, California3
Received 29 June 2007/ Accepted 29 August 2007
Campylobacter jejuni is the leading cause of bacterial gastroenteritis in the developed world. Despite its prevalence, relatively little is known about C. jejuni's precise pathogenesis mechanisms, particularly in comparison to other well-studied enteric organisms such as Escherichia coli and Salmonella spp. Altered expression of phosphate genes in a C. jejuni stringent response mutant, together with known correlations between the stringent response, polyphosphate (poly-P), and virulence in other bacteria, led us to investigate the role of poly-P in C. jejuni stress survival and pathogenesis. All sequenced C. jejuni strains harbor a conserved putative polyphosphate kinase 1 predicted to be principally responsible for poly-P synthesis. We generated a targeted ppk1 deletion mutant (
ppk1) in C. jejuni strain 81-176 and found that
ppk1, as well as the
spoT stringent response mutant, exhibited low levels of poly-P at all growth stages. In contrast, wild-type C. jejuni poly-P levels increased significantly as the bacteria transitioned from log to stationary phase. Phenotypic analyses revealed that the
ppk1 mutant was defective for survival during osmotic shock and low-nutrient stress. However, certain phenotypes associated with ppk1 deletion in other bacteria (i.e., motility and oxidative stress) were unaffected in the C. jejuni
ppk1 mutant, which also displayed an unexpected increase in biofilm formation. The C. jejuni
ppk1 mutant was also defective for the virulence-associated phenotype of intraepithelial cell survival in a tissue culture infection model and exhibited a striking, dose-dependent chick colonization defect. These results indicate that poly-P utilization and accumulation contribute significantly to C. jejuni pathogenesis and affect its ability to adapt to specific stresses and stringencies. Furthermore, our study demonstrates that poly-P likely plays both similar and unique roles in C. jejuni compared to its roles in other bacteria and that poly-P metabolism is linked to stringent response mechanisms in C. jejuni.
Published ahead of print on 7 September 2007.
Supplemental material for this article may be found at http://jb.asm.org/.
This article has been cited by other articles:
Copyright © 2009 by the American Society for Microbiology. For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»