title: Regulation of cell division in a temperature-sensitive division mutant of Escherichia coli.
abstract: Escherichia coli fil ts forms multinucleate filaments when suspensions of about 10(7) organisms per ml are shifted from 37 to 43 C in rich medium. Occasional septation continues, chiefly at the poles, and immediately becomes more frequent when the filaments are returned to 37 C. The addition of chloramphenicol (200 mug/ml) at either temperature initially stimulates the formation of polar septa. When very dilute suspensions of the strain (<10(6) organisms per ml) are shifted to the restrictive temperature, the inhibition of septation is more complete and only seldom reversible. Conversely, cell division is little affected when suspensions of >10(8) organisms per ml, or microcolonies of several hundred organisms on agar, are incubated at 43 C; evidence is presented that this is a consequence of a slight reduction in the mutant's growth rate. In certain media, septation is blocked irreversibly by even brief exposure to 43 C, after which cell elongation without division proceeds at 37 C for some hours. Several findings, when considered together, suggest that the cytoplasmic membrane is normal at the restrictive temperature, and that the block in septation is caused by a defect in the cell wall: it is largely overcome by NaCl, but not by sucrose; in some circumstances the filaments become swollen and develop localized bulges in the wall, yet the membrane remains intact and retains its selective permeability; lastly, the strain is insensitive to deoxycholate at both temperatures. The mutation has been mapped between arg B and thr, at a locus which appears to be distinct from others known primarily to influence cell division.
mesh_terms: D002455:Cell Division; D002463:Cell Membrane Permeability; D002701:Chloramphenicol / Q000494:pharmacology; D002874:Chromosome Mapping; D002876:Chromosomes, Bacterial; D003470:Culture Media; D004269:DNA, Bacterial / Q000096:biosynthesis; D003840:Deoxycholic Acid / Q000494:pharmacology; D004926:Escherichia coli / Q000254:growth & development* / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D006639:Histidine / Q000378:metabolism; D008715:Methionine / Q000378:metabolism; D009154:Mutation; D011995:Recombination, Genetic; D012965:Sodium Chloride / Q000494:pharmacology; D013395:Sucrose / Q000494:pharmacology; D013696:Temperature; D013997:Time Factors
chemical_list: D003470:Culture Media; D004269:DNA, Bacterial; D003840:Deoxycholic Acid; D012965:Sodium Chloride; D006639:Histidine; D013395:Sucrose; D002701:Chloramphenicol; D008715:Methionine; D005947:Glucose