Characterization of fmtA, a gene that modulates the expression of methicillin resistance in Staphylococcus aureus.
FmtA is a factor which affects the methicillin resistance level in methicillin-resistant Staphylococcus aureus. Since FmtA has two of three conserved motifs which are typically found in penicillin-binding proteins (PBPs) and beta-lactamases, we investigated the penicillin-binding activity of recombinant FmtA and found no such activity. Immunoblotting analysis revealed that FmtA localizes in the membrane fraction. To investigate the function of FmtA, high-pressure liquid chromatography analysis of cell wall muropeptides was performed with an fmtA-inactivated mutant and its parent. The mutant showed a reduced cross-linking and partially reduced amidation of glutamate residues in the peptidoglycan of the mutant. The transcription of fmtA was dose dependently increased by the addition of beta-lactam antibiotics, fosfomycin, and bacitracin, while its transcription was not changed by the addition of vancomycin or tetracycline. These results reveal that Fmt is a membrane-located, non-penicillin-binding protein and that mutation of fmtA affects the cell wall structure, although its precise function is still unknown.
Komatsuzawa
H
H
Department of Microbiology, Hiroshima University School of Dentistry, Kasumi 1-2-3, Minami-ku, Hiroshima City, Hiroshima 734-8553, Japan. hkomatsu@ipc.hiroshima-u.ac.jp
Ohta
K
K
Labischinski
H
H
Sugai
M
M
Suginaka
H
H
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002462:Cell Membrane / Q000187:drug effects; D002851:Chromatography, High Pressure Liquid; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects*; D019877:Hydroxymethyl and Formyl Transferases / Q000235:genetics*; D008712:Methicillin / Q000494:pharmacology; D016106:Methicillin Resistance / Q000235:genetics*; D008826:Microbial Sensitivity Tests; D009154:Mutation; D010406:Penicillins / Q000494:pharmacology; D010957:Plasmids / Q000145:classification / Q000187:drug effects; D013211:Staphylococcus aureus / Q000145:classification / Q000187:drug effects* / Q000235:genetics*
D000900:Anti-Bacterial Agents; D010406:Penicillins; D019877:Hydroxymethyl and Formyl Transferases; C021561:methionyl-tRNA formyltransferase; D008712:Methicillin