This Article Full Text (PDF) Other Versions of this Article: IAI.01619-06v1 75/6/2864    most recent 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 Matsunaga, J. Articles by Haake, D. A. Search for Related Content PubMed PubMed Citation Articles by Matsunaga, J. Articles by Haake, D. A.

 Previous Article  |  Next Article 

Infect. Immun. doi:10.1128/IAI.01619-06
Copyright (c) 2007, American Society for Microbiology and/or the Listed Authors/Institutions. All Rights Reserved.

Response of Leptospira interrogans to Physiologic Osmolarity: Relevance in Signaling the Environment-to-Host Transition

Veterans Affairs Greater Los Angeles Healthcare System, Research Service, Los Angeles, CA 90073; Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095; Australian Bacterial Pathogenesis Program, Monash University, Victoria 3800, Australia; Victorian Bioinformatics Consortium, Monash University, Victoria 3800, Australia; National Animal Disease Center, Agricultural Research Service, U.S. Department of Agriculture, Ames, Iowa 50010; Australian Research Council Centre of Excellence in Structural and Functional Microbial Genomics, Monash University, Victoria 3800, Australia; Division of Infectious Diseases, 111F, Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, CA 90073

^* To whom correspondence should be addressed. Email: jamesm{at}ucla.edu.

	Abstract

Transmission of pathogenic Leptospira between mammalian hosts usually involves dissemination via soil or water contaminated by the urine of carrier animals. The ability of Leptospira to adapt to the diverse conditions found inside and outside of the host is reflected in its relatively large genome size and high percentage of signal transduction genes. An exception is L. borgpetersenii serovar Hardjo, which is transmitted by direct contact and appears to have lost genes necessary for survival outside the mammalian host. Invasion of host tissues by L. interrogans involves a transition from a low osmolar environment outside the host to a higher physiologic osmolar environment within the host. Expression of the lipoprotein LigA and LigB adhesins is strongly induced by an upshift in osmolarity to the level found in mammalian host tissues. These data suggest Leptospira utilizes changes in osmolarity to regulate virulence characteristics. To better understand how L. interrogans serovar Copenhageni adapts to osmolar conditions that correspond with invasion of a mammalian host, we quantified alterations in transcript levels using whole-genome microarrays. Overnight exposure in leptospiral culture medium supplemented with sodium chloride to physiologic osmolarity significantly altered the transcript levels of 6% of L. interrogans genes. Repressed genes were significantly more likely to be absent or pseudogenes in L. borgpetersenii, suggesting that osmolarity is relevant in studying the adaptation of L. interrogans to host conditions. Genes induced by physiologic osmolarity encoded a higher than expected number of proteins involved in signal transduction. Further, genes predicted to encode lipoproteins and those co-regulated by temperature were overrepresented among both salt-induced and salt-repressed genes. In contrast, leptospiral homologues of hyperosmotic or general stress genes were not induced at physiologic osmolarity. These findings suggest that physiologic osmolarity is an important signal for pathogenic leptospires to regulate gene expression during transition from ambient conditions to the host tissue environment.

This article has been cited by other articles:

• Lin, Y.-P., Raman, R., Sharma, Y., Chang, Y.-F. (2008). Calcium Binds to Leptospiral Immunoglobulin-like Protein, LigB, and Modulates Fibronectin Binding. J. Biol. Chem. 283: 25140-25149 [Abstract] [Full Text]  
• Gancz, H., Jones, K. R., Merrell, D. S. (2008). Sodium Chloride Affects Helicobacter pylori Growth and Gene Expression. J. Bacteriol. 190: 4100-4105 [Abstract] [Full Text]  
• Matsunaga, J., Medeiros, M. A., Sanchez, Y., Werneid, K. F., Ko, A. I. (2007). Osmotic regulation of expression of two extracellular matrix-binding proteins and a haemolysin of Leptospira interrogans: differential effects on LigA and Sph2 extracellular release. Microbiology 153: 3390-3398 [Abstract] [Full Text]