Bacterial shape.
In free-living eubacteria an external shell of peptidoglycan opposes internal hydrostatic pressure and prevents membrane rupture and death. At the same time, this wall imposes on each cell a shape. Because shape is both stable and heritable, as is the ability of many organisms to execute defined morphological transformations, cells must actively choose from among a large repertoire of available shapes. How they do so has been debated for decades, but recently experiment has begun to catch up with theory. Two discoveries are particularly informative. First, specific protein assemblies, nucleated by FtsZ, MreB or Mbl, appear to act as internal scaffolds that influence cell shape, perhaps by correctly localizing synthetic enzymes. Second, defects in cell shape are correlated with the presence of inappropriately placed, metabolically inert patches of peptidoglycan. When combined with what we know about mutants affecting cellular morphology, these observations suggest that bacteria may fabricate specific shapes by directing the synthesis of two kinds of cell wall: a long-lived, rigid framework that defines overall topology, and a metabolically plastic peptidoglycan whose shape is directed by internal scaffolds.
Young
Kevin D
KD
Department of Microbiology and Immunology, University of North Dakota School of Medicine, Grand Forks 58202-9037, USA. kyoung@medicine.nodak.edu
D000251:Adenosine Triphosphatases / Q000235:genetics / Q000502:physiology; D001419:Bacteria / Q000166:cytology* / Q000187:drug effects / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology; D002352:Carrier Proteins / Q000235:genetics / Q000502:physiology; D018797:Cell Cycle Proteins; D002455:Cell Division; D002473:Cell Wall / Q000187:drug effects / Q000648:ultrastructure*; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000502:physiology; D004261:DNA Replication; D004269:DNA, Bacterial / Q000096:biosynthesis; D029968:Escherichia coli Proteins / Q000235:genetics / Q000502:physiology*; D006602:Hexosyltransferases / Q000235:genetics / Q000502:physiology; D008565:Membrane Proteins / Q000235:genetics / Q000502:physiology; D008954:Models, Biological; D009024:Morphogenesis; D002267:Muramoylpentapeptide Carboxypeptidase / Q000235:genetics / Q000502:physiology; D009997:Osmotic Pressure; D046915:Penicillin-Binding Proteins; D010406:Penicillins / Q000494:pharmacology; D010457:Peptidoglycan / Q000378:metabolism* / Q000648:ultrastructure; D010458:Peptidyl Transferases / Q000235:genetics / Q000502:physiology; D013045:Species Specificity
D001426:Bacterial Proteins; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D003598:Cytoskeletal Proteins; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; C076835:FtsZ84 protein, E coli; D008565:Membrane Proteins; C462942:MinC protein, E coli; C093548:MinE protein, E coli; D046915:Penicillin-Binding Proteins; D010406:Penicillins; D010457:Peptidoglycan; C424044:mbl protein, Bacillus subtilis; D010458:Peptidyl Transferases; D006602:Hexosyltransferases; D002267:Muramoylpentapeptide Carboxypeptidase; D000251:Adenosine Triphosphatases; C072069:MinD protein, E coli