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EMBO J. Sep 1, 1997; 16(17): 5376–5385.
PMCID: PMC1170169

The Salmonella selC locus contains a pathogenicity island mediating intramacrophage survival.


Pathogenicity islands are chromosomal clusters of horizontally acquired virulence genes that are often found at tRNA loci. The selC tRNA locus of Escherichia coli has served as the site of integration of two distinct pathogenicity islands which are responsible for converting benign strains into uro- and enteropathogens. Because virulence genes are targeted to the selC locus of E.coli, we investigated the homologous region of the Salmonella typhimurium chromosome for the presence of horizontally acquired sequences. At this site, we identified a 17 kb DNA segment that is both unique to Salmonella and necessary for virulence. This segment harbors a gene, mgtC, that is required for intramacrophage survival and growth in low Mg2+ media. The mgtC locus is regulated by the PhoP/PhoQ two-component system, a major regulator of virulence functions present in both pathogenic and non-pathogenic bacterial species. Cumulatively, our experiments indicate that the ability to replicate in low Mg2+ environments is necessary for Salmonella virulence, and suggest that a similar mechanism is responsible for the dissemination and acquisition of pathogenicity islands in enteric bacteria.

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Selected References

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  • Ahmad S, Weisburg WG, Jensen RA. Evolution of aromatic amino acid biosynthesis and application to the fine-tuned phylogenetic positioning of enteric bacteria. J Bacteriol. 1990 Feb;172(2):1051–1061. [PMC free article] [PubMed]
  • Bajaj V, Lucas RL, Hwang C, Lee CA. Co-ordinate regulation of Salmonella typhimurium invasion genes by environmental and regulatory factors is mediated by control of hilA expression. Mol Microbiol. 1996 Nov;22(4):703–714. [PubMed]
  • Blum G, Ott M, Lischewski A, Ritter A, Imrich H, Tschäpe H, Hacker J. Excision of large DNA regions termed pathogenicity islands from tRNA-specific loci in the chromosome of an Escherichia coli wild-type pathogen. Infect Immun. 1994 Feb;62(2):606–614. [PMC free article] [PubMed]
  • Bolivar F, Rodriguez RL, Greene PJ, Betlach MC, Heyneker HL, Boyer HW, Crosa JH, Falkow S. Construction and characterization of new cloning vehicles. II. A multipurpose cloning system. Gene. 1977;2(2):95–113. [PubMed]
  • Boyd EF, Wang FS, Whittam TS, Selander RK. Molecular genetic relationships of the salmonellae. Appl Environ Microbiol. 1996 Mar;62(3):804–808. [PMC free article] [PubMed]
  • Buluwela L, Forster A, Boehm T, Rabbitts TH. A rapid procedure for colony screening using nylon filters. Nucleic Acids Res. 1989 Jan 11;17(1):452–452. [PMC free article] [PubMed]
  • McDaniel TK, Kaper JB. A cloned pathogenicity island from enteropathogenic Escherichia coli confers the attaching and effacing phenotype on E. coli K-12. Mol Microbiol. 1997 Jan;23(2):399–407. [PubMed]
  • McDaniel TK, Jarvis KG, Donnenberg MS, Kaper JB. A genetic locus of enterocyte effacement conserved among diverse enterobacterial pathogens. Proc Natl Acad Sci U S A. 1995 Feb 28;92(5):1664–1668. [PMC free article] [PubMed]
  • Casadaban MJ, Cohen SN. Analysis of gene control signals by DNA fusion and cloning in Escherichia coli. J Mol Biol. 1980 Apr;138(2):179–207. [PubMed]
  • Fields PI, Groisman EA, Heffron F. A Salmonella locus that controls resistance to microbicidal proteins from phagocytic cells. Science. 1989 Feb 24;243(4894 Pt 1):1059–1062. [PubMed]
  • Mills DM, Bajaj V, Lee CA. A 40 kb chromosomal fragment encoding Salmonella typhimurium invasion genes is absent from the corresponding region of the Escherichia coli K-12 chromosome. Mol Microbiol. 1995 Feb;15(4):749–759. [PubMed]
  • Galán JE. Molecular genetic bases of Salmonella entry into host cells. Mol Microbiol. 1996 Apr;20(2):263–271. [PubMed]
  • Garcia Véscovi E, Soncini FC, Groisman EA. The role of the PhoP/PhoQ regulon in Salmonella virulence. Res Microbiol. 1994 Jun-Aug;145(5-6):473–480. [PubMed]
  • Ochman H, Soncini FC, Solomon F, Groisman EA. Identification of a pathogenicity island required for Salmonella survival in host cells. Proc Natl Acad Sci U S A. 1996 Jul 23;93(15):7800–7804. [PMC free article] [PubMed]
  • Reinhart RA. Magnesium metabolism. A review with special reference to the relationship between intracellular content and serum levels. Arch Intern Med. 1988 Nov;148(11):2415–2420. [PubMed]
  • Garcia-del Portillo F, Foster JW, Maguire ME, Finlay BB. Characterization of the micro-environment of Salmonella typhimurium-containing vacuoles within MDCK epithelial cells. Mol Microbiol. 1992 Nov;6(22):3289–3297. [PubMed]
  • Sanderson KE, Hessel A, Rudd KE. Genetic map of Salmonella typhimurium, edition VIII. Microbiol Rev. 1995 Jun;59(2):241–303. [PMC free article] [PubMed]
  • Shea JE, Hensel M, Gleeson C, Holden DW. Identification of a virulence locus encoding a second type III secretion system in Salmonella typhimurium. Proc Natl Acad Sci U S A. 1996 Mar 19;93(6):2593–2597. [PMC free article] [PubMed]
  • Groisman EA, Ochman H. How to become a pathogen. Trends Microbiol. 1994 Aug;2(8):289–294. [PubMed]
  • Groisman EA, Ochman H. Pathogenicity islands: bacterial evolution in quantum leaps. Cell. 1996 Nov 29;87(5):791–794. [PubMed]
  • Groisman EA, Chiao E, Lipps CJ, Heffron F. Salmonella typhimurium phoP virulence gene is a transcriptional regulator. Proc Natl Acad Sci U S A. 1989 Sep;86(18):7077–7081. [PMC free article] [PubMed]
  • Groisman EA, Sturmoski MA, Solomon FR, Lin R, Ochman H. Molecular, functional, and evolutionary analysis of sequences specific to Salmonella. Proc Natl Acad Sci U S A. 1993 Feb 1;90(3):1033–1037. [PMC free article] [PubMed]
  • Gulig PA, Danbara H, Guiney DG, Lax AJ, Norel F, Rhen M. Molecular analysis of spv virulence genes of the Salmonella virulence plasmids. Mol Microbiol. 1993 Mar;7(6):825–830. [PubMed]
  • Swenson DL, Bukanov NO, Berg DE, Welch RA. Two pathogenicity islands in uropathogenic Escherichia coli J96: cosmid cloning and sample sequencing. Infect Immun. 1996 Sep;64(9):3736–3743. [PMC free article] [PubMed]
  • Gunn JS, Alpuche-Aranda CM, Loomis WP, Belden WJ, Miller SI. Characterization of the Salmonella typhimurium pagC/pagD chromosomal region. J Bacteriol. 1995 Sep;177(17):5040–5047. [PMC free article] [PubMed]
  • Tao T, Snavely MD, Farr SG, Maguire ME. Magnesium transport in Salmonella typhimurium: mgtA encodes a P-type ATPase and is regulated by Mg2+ in a manner similar to that of the mgtB P-type ATPase. J Bacteriol. 1995 May;177(10):2654–2662. [PMC free article] [PubMed]
  • Hacker J, Blum-Oehler G, Mühldorfer I, Tschäpe H. Pathogenicity islands of virulent bacteria: structure, function and impact on microbial evolution. Mol Microbiol. 1997 Mar;23(6):1089–1097. [PubMed]
  • Heithoff DM, Conner CP, Hanna PC, Julio SM, Hentschel U, Mahan MJ. Bacterial infection as assessed by in vivo gene expression. Proc Natl Acad Sci U S A. 1997 Feb 4;94(3):934–939. [PMC free article] [PubMed]
  • Hensel M, Shea JE, Bäumler AJ, Gleeson C, Blattner F, Holden DW. Analysis of the boundaries of Salmonella pathogenicity island 2 and the corresponding chromosomal region of Escherichia coli K-12. J Bacteriol. 1997 Feb;179(4):1105–1111. [PMC free article] [PubMed]
  • Hmiel SP, Snavely MD, Florer JB, Maguire ME, Miller CG. Magnesium transport in Salmonella typhimurium: genetic characterization and cloning of three magnesium transport loci. J Bacteriol. 1989 Sep;171(9):4742–4751. [PMC free article] [PubMed]
  • Hohmann EL, Oletta CA, Loomis WP, Miller SI. Macrophage-inducible expression of a model antigen in Salmonella typhimurium enhances immunogenicity. Proc Natl Acad Sci U S A. 1995 Mar 28;92(7):2904–2908. [PMC free article] [PubMed]
  • Inouye S, Sunshine MG, Six EW, Inouye M. Retronphage phi R73: an E. coli phage that contains a retroelement and integrates into a tRNA gene. Science. 1991 May 17;252(5008):969–971. [PubMed]
  • Klose KE, Mekalanos JJ. Simultaneous prevention of glutamine synthesis and high-affinity transport attenuates Salmonella typhimurium virulence. Infect Immun. 1997 Feb;65(2):587–596. [PMC free article] [PubMed]

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