title: Penicillin-resistant temperature-sensitive mutants of Escherichia coli which synthesize hypo- or hyper-cross-linked peptidoglycan.
abstract: A group of Escherichia coli mutants which are ampicillin resistant at 32 C and which either are unable to grow or lyse at 42 C has been selected. These mutants have been classified by a number of characteristics: total peptidoglycan synthesis measured by [(14)C]diaminopimelic acid incorporation, extent of cross-linking of the peptidoglycan which is synthesized, growth characteristics at the two temperatures, and morphology. Two especially interesting groups of mutants have been described. In one of these, a hypo-cross-linked peptidoglycan was synthesized at the nonpermissive temperature. Most of these organisms lysed at 42 C. In another group, the peptidoglycan synthesized at 42 C was hyper-cross-linked. Many of these organisms were spherical. Studies of revertants indicated that ampicillin resistance, temperature sensitivity, cross-linking, growth characteristics, and morphological changes may be related to a single mutational event in both of these groups.
mesh_terms: D000667:Ampicillin / Q000494:pharmacology; D001345:Autoradiography; D001433:Bacteriolysis; D002250:Carbon Radioisotopes; D004926:Escherichia coli / Q000145:classification / Q000166:cytology / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*; D008858:Microscopy, Phase-Contrast; D009153:Mutagens; D009154:Mutation; D009604:Nitrosoguanidines; D010403:Penicillin Resistance; D010457:Peptidoglycan / Q000096:biosynthesis*; D010867:Pimelic Acids / Q000378:metabolism; D013696:Temperature
chemical_list: D002250:Carbon Radioisotopes; D009153:Mutagens; D009604:Nitrosoguanidines; D010457:Peptidoglycan; D010867:Pimelic Acids; D000667:Ampicillin