Identification of virulence determinants for endocarditis in Streptococcus sanguinis by signature-tagged mutagenesis

Sehmi Paik, Lauren Senty, Sankar Das, Jody C. Noe, Cindy Munro, Todd Kitten

Research output: Contribution to journalArticle

52 Citations (Scopus)

Abstract

Streptococcus sanguinis is a gram-positive, facultative anaerobe and a normal inhabitant of the human oral cavity. It is also one of the most common agents of infective endocarditis, a serious endovascular infection. To identify virulence factors for infective endocarditis, signature-tagged mutagenesis (STM) was applied to the SK36 strain of S. sanguinis, whose genome is being sequenced. STM allows the large-scale creation, in vivo screening, and recovery of a series of mutants with altered virulence. Screening of 800 mutants by STM identified 38 putative avirulent and 5 putative hypervirulent mutants. Subsequent molecular analysis of a subset of these mutants identified genes encoding undecaprenol kinase, homoserine kinase, anaerobic ribonucleotide reductase, adenylosuccinate lyase, and a hypothetical protein. Virulence reductions ranging from 2-to 150-fold were confirmed by competitive index assays. One putatively hypervirulent strain with a transposon insertion in an intergenic region was identified, though increased virulence was not confirmed in competitive index assays. All mutants grew comparably to SK36 in aerobic broth culture except for the homoserine kinase mutant. Growth of this mutant was restored by the addition of threonine to the medium. Mutants containing an insertion or in-frame deletion in the anaerobic ribonucleotide reductase gene failed to grow under strictly anaerobic conditions. The results suggest that housekeeping functions such as cell wall synthesis, amino acid and nucleic acid synthesis, and the ability to survive under anaerobic conditions are important virulence factors in S. sanguinis endocarditis.

Original languageEnglish (US)
Pages (from-to)6064-6074
Number of pages11
JournalInfection and Immunity
Volume73
Issue number9
DOIs
StatePublished - Sep 1 2005
Externally publishedYes

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homoserine kinase
Endocarditis
Streptococcus
Mutagenesis
Virulence
undecaprenol kinase
Virulence Factors
Adenylosuccinate Lyase
Housekeeping
Intergenic DNA
Threonine
Cell Wall
Nucleic Acids
Genes
Mouth
Genome
Amino Acids
Growth
Infection
Proteins

ASJC Scopus subject areas

  • Parasitology
  • Microbiology
  • Immunology
  • Infectious Diseases

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Identification of virulence determinants for endocarditis in Streptococcus sanguinis by signature-tagged mutagenesis. / Paik, Sehmi; Senty, Lauren; Das, Sankar; Noe, Jody C.; Munro, Cindy; Kitten, Todd.

In: Infection and Immunity, Vol. 73, No. 9, 01.09.2005, p. 6064-6074.

Research output: Contribution to journalArticle

Paik, Sehmi ; Senty, Lauren ; Das, Sankar ; Noe, Jody C. ; Munro, Cindy ; Kitten, Todd. / Identification of virulence determinants for endocarditis in Streptococcus sanguinis by signature-tagged mutagenesis. In: Infection and Immunity. 2005 ; Vol. 73, No. 9. pp. 6064-6074.
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