Branching of Escherichia coli cells arises from multiple sites of inert peptidoglycan.
Some strains of Escherichia coli defective for dacA, the gene coding for penicillin-binding protein 5, exhibit a strong branching phenotype when cell division is blocked. Since such branch formation implies a differentiation of polar caps at ectopic locations in the cell envelope, we analyzed murein segregation and observed a strong correlation between areas of inert murein and these morphological anomalies. In particular, the tips of branches exhibited the same properties as those described for polar caps of wild-type cells, i.e., the synthesis and turnover of murein were inhibited. Also, the mobility of cell envelope proteins was apparently constrained in areas with morphological defects. Polar regions of branching cells and sacculi had aberrant morphologies with a very high frequency. Of special interest was that areas of inert murein at polar caps were often split by areas of active synthesis, a situation unlike that observed in wild-type cells. These observations suggest that in dacA mutants, branches and other morphological anomalies may arise from split polar caps or by de novo generation of new poles built around inert peptidoglycan patches in the side walls of the cell.
de Pedro
Miguel A
MA
Centro de Biología Molecular "Severo Ochoa," Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Campus de Cantoblanco, 28049 Madrid, Spain. madepedro@cbm.uam.es
Young
Kevin D
KD
Höltje
Joachim-Volker
JV
Schwarz
Heinz
H
D001426:Bacterial Proteins; D002352:Carrier Proteins / Q000235:genetics; D002455:Cell Division; D004926:Escherichia coli / Q000235:genetics / Q000648:ultrastructure*; D029968:Escherichia coli Proteins / Q000378:metabolism; D006602:Hexosyltransferases; D018613:Microscopy, Confocal; D002267:Muramoylpentapeptide Carboxypeptidase / Q000235:genetics; D046915:Penicillin-Binding Proteins; D010457:Peptidoglycan / Q000378:metabolism*; D010458:Peptidyl Transferases
D001426:Bacterial Proteins; D002352:Carrier Proteins; D029968:Escherichia coli Proteins; D046915:Penicillin-Binding Proteins; D010457:Peptidoglycan; D010458:Peptidyl Transferases; D006602:Hexosyltransferases; D002267:Muramoylpentapeptide Carboxypeptidase