Table 1

Bacterial strains and plasmids used in this study

Strain or plasmidDescriptionaβ-Lactam resistance phenotypeReference(s)
Strains
    N315Japanese clinical pre-MRSA strain carrying a functional mecI encoding mecA gene repressorPre-MRSA11
    N315ΔIPmecI null mutant derived from N315P, an N315-derivative strain with the penicillinase plasmid eliminatedHetero-type12
    ΔIP-H5Mutant derived from N315ΔIP by selection with 8 mg/liter of imipenem, carrying rpoB(N967I)Homo-type30
    ΔIP-H14Mutant derived from N315ΔIP by selection with 8 mg/liter of imipenem, carrying vraS(S329L)Homo-type20, 30
    N315h4Mutant derived from N315 by selection with 128 mg/liter of methicillinEagle-type10
    H5 rpoB(I967N)ΔIP-H5 in which rpoB(I967) is replaced by the wild-type rpoBHetero-typeThis study
    N315 rpoB(N967I)N315 whose wild-type rpoB is replaced by rpoB(967I) mutationEagle-typeThis study
Plasmids
    pKOR1E. coli-S. aureus shuttle vector for construction of allelic replacement26
    pKOR1-rpoB(967I)pKOR1 harboring the 1,820-bp PCR product of mutated rpoB carrying amino acid residue Ile at position 967This study
    pKOR1-rpoB(967N)pKOR1 harboring the 1,820-bp PCR product of wild-type rpoB carrying amino acid residue Asn at position 967This study
  • a Strains obtained by antibiotic selection are denoted as mutant.