Spontaneous pmrA mutants of Salmonella typhimurium LT2 define a new two- component regulatory system with a possible role in virulence

K. L. Roland, L. E. Martin, C. R. Esther, J. K. Spitznagel

Research output: Contribution to journalArticle

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Abstract

We isolated spontaneous mutations (pmrA) in the smooth strain Salmonella typhimurium LT2 that show increased resistance to the cationic antibacterial proteins of human neutrophils and to the drug polymyxin B. The mutation in one strain, JKS5, maps to 93 min on the S. typhimurium chromosome, near the proP gene and the melAB operon. The mutation, designated pmrA505, confers a 1,000-fold increase in resistance to polymyxin B and a 2- to 4-fold increase in resistance to neutrophil proteins. We cloned both the pmrA505 and pmrA+ alleles and found that the pmrA+ gene is partially dominant over pmrA505. DNA sequence analysis of the pmrA505 clone revealed three open reading frames (ORFs). The deduced amino acid sequences indicated that ORF1 encodes a 548- amino-acid (aa) protein with a putative membrane-spanning domain and no significant homology to any known protein. ORF2 and ORF3, which encode 222- and 356-aa proteins, respectively, show strong homology with the OmpR-EnvZ family of two-component regulatory systems. ORF2 showed homology with a number of response regulators, including OmpR and PhoP, while ORF3 showed homology to histidine kinase-sensor proteins EnvZ and PhoR. Genetic analysis of the cloned genes suggested that ORF2 contained the pmrA505 mutation. Comparison of the pmrA505 and pmrA+ ORF2 DNA sequences revealed a single G- A transition, which would result in a His-to-Arg substitution at position 81 in the ORF2 mutant protein. We therefore designate ORF2 PmrA and ORF3 PmrB. The function of ORF1 is unknown.

Original languageEnglish (US)
Pages (from-to)4154-4164
Number of pages11
JournalJournal of Bacteriology
Volume175
Issue number13
StatePublished - 1993
Externally publishedYes

Fingerprint

Salmonella typhimurium
Virulence
Polymyxin B
Mutation
Proteins
Neutrophils
Genes
Amino Acids
Mutant Proteins
Operon
DNA Sequence Analysis
Open Reading Frames
Amino Acid Sequence
Clone Cells
Chromosomes
Alleles
Membranes
Pharmaceutical Preparations

ASJC Scopus subject areas

  • Applied Microbiology and Biotechnology
  • Immunology

Cite this

Spontaneous pmrA mutants of Salmonella typhimurium LT2 define a new two- component regulatory system with a possible role in virulence. / Roland, K. L.; Martin, L. E.; Esther, C. R.; Spitznagel, J. K.

In: Journal of Bacteriology, Vol. 175, No. 13, 1993, p. 4154-4164.

Research output: Contribution to journalArticle

Roland, K. L. ; Martin, L. E. ; Esther, C. R. ; Spitznagel, J. K. / Spontaneous pmrA mutants of Salmonella typhimurium LT2 define a new two- component regulatory system with a possible role in virulence. In: Journal of Bacteriology. 1993 ; Vol. 175, No. 13. pp. 4154-4164.
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