Infection and Immunity, December 1998, p. 5599-5606, Vol. 66, No. 12
Megan Health, Inc., St. Louis, Missouri
63110,1 and
Department of Biology,
Washington University, St. Louis, Missouri 631302
Received 2 January 1998/Returned for modification 30 March
1998/Accepted 28 September 1998
Salmonella enterica poxA mutants exhibit a pleiotropic
phenotype, including reduced pyruvate oxidase activity; reduced growth rate; and hypersensitivity to the herbicide sulfometuron methyl,
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Copyright © 1998, American Society for Microbiology. All rights reserved.
Molecular and Functional Characterization of
Salmonella enterica Serovar Typhimurium poxA
Gene: Effect on Attenuation of Virulence and Protection
-ketobutyrate, and amino acid analogs. These mutants also failed to
grow in the presence of the host antimicrobial peptide, protamine. In
this study, PoxA
mutants of S. enterica
serovar Typhimurium (S. typhimurium) were found to be
10,000-fold attenuated in orally inoculated BALB/c mice and 1,000-fold
attenuated in intraperitoneally inoculated BALB/c mice, compared to
wild-type S. typhimurium UK-1. In addition, poxA mutants were found to be capable of colonizing the
spleen, mesenteric lymph nodes, and Peyer's patches; to induce strong humoral immune responses; and to protect mice against a lethal wild-type Salmonella challenge. A 2-kb DNA fragment was
isolated from wild-type S. typhimurium UK-1 based on its
ability to complement an isogenic poxA mutant. The
nucleotide sequence of this DNA fragment revealed an open reading frame
of 325 amino acids capable of encoding a polypeptide of 36.8 kDa that
was confirmed in the bacteriophage T7 expression system. Comparison of
the translated sequence to the available databases indicated high
homology to a family of lysyl-tRNA synthetases. Our results indicate
that a mutation of poxA has an attenuating effect on
Salmonella virulence. Further, poxA mutants are
immunogenic and could be useful in designing live vaccines with a
variety of bacterial species. To our knowledge, this is the first
report on the effect of poxA mutation on bacterial virulence.
*
Corresponding author. Mailing address: Megan Health,
Inc., 3655 Vista Ave., St. Louis, MO 63110. Phone: (314) 776-1626, ext. 104. Fax: (314) 776-3317. E-mail: kkaniga{at}meganhealth.com.
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