title: A link in transcription between the native pbpB and the acquired mecA gene in a strain of Staphylococcus aureus.
abstract: Conditional mutants of pbpB with an IPTG-inducible promoter were used to compare the effects of interrupted transcription of this gene in a meticillin-sensitive (MSSA) and a meticillin-resistant (MRSA) strain of Staphylococcus aureus. After 3 h growth following the removal of IPTG, multiplication of the MSSA strain stopped abruptly, cells began to lyse, and membrane preparations showed greatly decreased quantities of penicillin-binding protein (PBP) 2. In contrast, the MRSA strain continued to grow for at least 20 h in the IPTG-free medium, but with gradually increasing doubling times, which eventually reached 180 min. The peptidoglycan produced during this period of extremely slow growth showed only minor alterations, but cells with abnormal morphology accumulated in the culture, the abundance of mecA transcript gradually declined, and the cellular amounts of PBP2A were significantly decreased. Adding back the IPTG inducer caused rapid resumption in the transcription of pbpB, followed by an increase in the transcription of mecA. No changes were detected in the transcription of pbpA, C and D, the determinant of 16S rRNA or the housekeeping gene pta. Promoter fusion experiments suggested that the transcription of the resistance gene mecA may respond to some regulatory signal generated in the bacteria during changes in the transcription of pbpB.
authors.affiliation: Laboratory of Microbiology, The Rockefeller University, 1230 York Avenue, NY 10021, USA.|Molecular Genetics Laboratory, Instituto de Tecnologia Química e Biológica da Universidade Nova de Lisboa, 2780 Oeiras, Portugal.
authors.forename: Susana
authors.initials: S
authors.lastname: Gardete
authors.affiliation: Laboratory of Microbiology, The Rockefeller University, 1230 York Avenue, NY 10021, USA.|Molecular Genetics Laboratory, Instituto de Tecnologia Química e Biológica da Universidade Nova de Lisboa, 2780 Oeiras, Portugal.
authors.forename: Hermínia
authors.initials: H
authors.lastname: de Lencastre
authors.affiliation: Laboratory of Microbiology, The Rockefeller University, 1230 York Avenue, NY 10021, USA.
authors.forename: Alexander
authors.initials: A
authors.lastname: Tomasz
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D005798:Genes, Bacterial; D007544:Isopropyl Thiogalactoside / Q000494:pharmacology; D008712:Methicillin / Q000494:pharmacology*; D016106:Methicillin Resistance / Q000235:genetics; D008826:Microbial Sensitivity Tests; D009154:Mutation; D046915:Penicillin-Binding Proteins / Q000235:genetics* / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D015203:Reproducibility of Results; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D046915:Penicillin-Binding Proteins; D007544:Isopropyl Thiogalactoside; D008712:Methicillin