Genomic Rearrangements at rrn Operons in Salmonella

Corresponding author: Stanley Maloy, San Diego State University, 5500 Campanile Dr., San Diego, CA 92182-4614., smaloy{at}sciences.sdsu.edu (E-mail)

Communicating editor: A. SONENSHEIN

Most Salmonella serovars are general pathogens that infect a variety of hosts. These "generalist" serovars cause disease in many animals from reptiles to mammals. In contrast, a few serovars cause disease only in a specific host. Host-specific serovars can cause a systemic, often fatal disease in one species yet remain avirulent in other species. Host-specific Salmonella frequently have large genomic rearrangements due to recombination at the ribosomal RNA (rrn) operons while the generalists consistently have a conserved chromosomal arrangement. To determine whether this is the result of an intrinsic difference in recombination frequency or a consequence of lifestyle difference between generalist and host-specific Salmonella, we determined the frequency of rearrangements in vitro. Using lacZ genes as portable regions of homology for inversion analysis, we found that both generalist and host-specific serovars of Salmonella have similar tolerances to chromosomal rearrangements in vitro. Using PCR and genetic selection, we found that generalist and host-specific serovars also undergo rearrangements at rrn operons at similar frequencies in vitro. These observations indicate that the observed difference in genomic stability between generalist and host-specific serovars is a consequence of their distinct lifestyles, not intrinsic differences in recombination frequencies.

This article has been cited by other articles:

				W.-C. Huang, Y.-Y. M. Chen, L.-J. Teng, H.-T. Lien, J.-Y. Chen, and J.-S. Chia Chromosomal inversion between rrn operons among Streptococcus mutans serotype c oral and blood isolates J. Med. Microbiol., February 1, 2008; 57(2): 198 - 206. [Abstract] [Full Text] [PDF]

				M. M. Brinig, C. A. Cummings, G. N. Sanden, P. Stefanelli, A. Lawrence, and D. A. Relman Significant Gene Order and Expression Differences in Bordetella pertussis Despite Limited Gene Content Variation. J. Bacteriol., April 1, 2006; 188(7): 2375 - 2382. [Abstract] [Full Text] [PDF]

				L. H. Conlan, M. J. Stanger, K. Ichiyanagi, and M. Belfort Localization, mobility and fidelity of retrotransposed Group II introns in rRNA genes Nucleic Acids Res., September 16, 2005; 33(16): 5262 - 5270. [Abstract] [Full Text] [PDF]

				K.-Y. Wu, G.-R. Liu, W.-Q. Liu, A. Q. Wang, S. Zhan, K. E. Sanderson, R. N. Johnston, and S.-L. Liu The Genome of Salmonella enterica Serovar Gallinarum: Distinct Insertions/Deletions and Rare Rearrangements J. Bacteriol., July 15, 2005; 187(14): 4720 - 4727. [Abstract] [Full Text] [PDF]

				S. Kothapalli, S. Nair, S. Alokam, T. Pang, R. Khakhria, D. Woodward, W. Johnson, B. A. D. Stocker, K. E. Sanderson, and S.-L. Liu Diversity of Genome Structure in Salmonella enterica Serovar Typhi Populations J. Bacteriol., April 15, 2005; 187(8): 2638 - 2650. [Abstract] [Full Text] [PDF]

				R. A. Helm, S. Porwollik, A. E. Stanley, S. Maloy, M. McClelland, W. Rabsch, and A. Eisenstark Pigeon-Associated Strains of Salmonella enterica Serovar Typhimurium Phage Type DT2 Have Genomic Rearrangements at rRNA Operons Infect. Immun., December 1, 2004; 72(12): 7338 - 7341. [Abstract] [Full Text] [PDF]