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An M protein with a single C repeat prevents phagocytosis of Streptococcus pyogenes : use of a temperature‐sensitive shuttle vector to deliver homologous sequences to the chromosome of S. pyogenes
Author(s) -
PerezCasal José,
Price Jennifer Ayres,
Maguin Emmanuelle,
Scott June R.
Publication year - 1993
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.1993.tb01628.x
Subject(s) - streptococcus pyogenes , biology , shuttle vector , homologous recombination , virulence , homologous chromosome , microbiology and biotechnology , dna , mutant , genetics , phagocytosis , bacteria , recombinant dna , vector (molecular biology) , gene , staphylococcus aureus
Summary The major virulence factor of the important human pathogen Streptococcus pyogenes is the M protein, which prevents phagocytosis of the bacterium. In different strains of streptococci, there are over 80 serologically different M proteins and there are additional M‐like proteins, some of which bind immunoglobulins. Although the sequence of the M molecules differs among different S. pyogenes strains, all M proteins, and some of the immunogiobulin‐binding molecules, have at least two copies of the C repeat region. We describe construction of a deletion mutation in S. pyogenes , which has only one C repeat copy, and show that the mutant strain is still resistant to phagocytosis. The mutation was constructed in vitro and used to replace the resident emm allele in an S. pyogenes strain. To facilitate homologous recombination into the streptococcal chromosome, we adapted a shuttle vector which is temperature sensitive for replication in Gram‐positive bacteria but not in Gram‐negative hosts. This new method for delivery of a homologous DNA fragment to the S. pyogenes chromosome is efficient and reproducible and should be of general use.