Open AccessRole of PBP1 in Cell Division of Staphylococcus aureus
Author(s) -
Sandro F. F. Pereira,
Adriano O. Henriques,
Mariana G. Pinho,
Hermı́nia de Lencastre,
Alexander Tomasz
Publication year - 2007
Publication title -
journal of bacteriology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.652
H-Index - 246
eISSN - 1067-8832
pISSN - 0021-9193
DOI - 10.1128/jb.00044-07
Subject(s) - peptidoglycan , biology , cell division , mutant , microbiology and biotechnology , bacterial cell structure , population , cell wall , cell , lac operon , bacteria , gene , genetics , gene expression , demography , sociology
We constructed a conditional mutant ofpbpA in which transcription of the gene was placed under the control of an IPTG (isopropyl-β-d -thiogalactopyranoside)-inducible promoter in order to explore the role of PBP1 in growth, cell wall structure, and cell division. A methicillin-resistant strain and an isogenic methicillin-susceptible strain, each carrying thepbpA mutation, were unable to grow in the absence of the inducer. Conditional mutants ofpbpA transferred into IPTG-free medium underwent a four- to fivefold increase in cell mass, which was not accompanied by a proportional increase in viable titer. Examination of thin sections of such cells by transmission electron microscopy or fluorescence microscopy of intact cells with Nile red-stained membranes showed a morphologically heterogeneous population of bacteria with abnormally increased sizes, distorted axial ratios, and a deficit in the number of cells with completed septa. Immunofluorescence with an antibody specific for PBP1 localized the protein to sites of cell division. No alteration in the composition of peptidoglycan was detectable inpbpA conditional mutants grown in the presence of a suboptimal concentration of IPTG, which severely restricted the rate of growth, and the essential function of PBP1 could not be replaced by PBP2A present in methicillin-resistant cells. These observations suggest that PBP1 is not a major contributor to the cross-linking of peptidoglycan and that its essential function must be intimately integrated into the mechanism of cell division.