A PBP 2 mutant devoid of the transpeptidase domain abolishes spermine-β-lactam synergy in Staphylococcus aureus Mu50.

ABSTRACT: Exogenous spermine was reported to enhance the killing of methicillin-resistant Staphylococcus aureus (MRSA) by β-lactams through a strong synergistic effect of unknown nature. Spermine alone also exerts an antimicrobial activity against S. aureus in a pH-dependent manner. MIC measurements revealed stronger effects of spermine under alkaline conditions, suggesting the nucleophilic property of spermine instead of its positive charge as the cause of adverse effects. A spontaneous suppressor mutant (MuM) of MRSA Mu50 was selected for spermine resistance and conferred complete abolishment of spermine-β-lactam synergy. In comparison to that in Mu50, the spermine MIC in MuM remained constant (64 mM) at pH 6 to 8; however, MuM, a heat-sensitive mutant, also grew in a very narrow pH range. Further

SUBMITTER: Yao X 

PROVIDER: S-EPMC3256068 | biostudies-literature | 2012 Jan

REPOSITORIES: biostudies-literature