title: Temperature-sensitive murein synthesis in an Escherichia coli pdx mutant and the role of alanine racemase.
abstract: The basis for disruption of morphogenesis by depletion of pyridoxine derivatives was studied using a pdxH null mutant of Escherichia coli K-12. Removal of pyridoxal from growing cultures severely inhibited murein synthesis in vivo, whereas simultaneous supplementation with D-alanine effectively prevented inhibition. Extractable alanine racemase was low following such starvation. Selection of mutants overcoming the glycine- or temperature-sensitivity imposed by pyridoxine limitation yielded a variety of phenotypes. The most effective of these extragenic suppressors conferred an elevated alanine racemase activity which was resistant to the effects of pyridoxal removal.
authors.affiliation: Department of Microbiology, University of Illinois, Urbana 61801.
authors.forename: D W
authors.initials: DW
authors.lastname: Grogan
mesh_terms: D000409:Alanine / Q000378:metabolism; D000411:Alanine Racemase / Q000378:metabolism*; D000591:Amino Acid Isomerases / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D009154:Mutation; D010457:Peptidoglycan / Q000096:biosynthesis*; D011730:Pyridoxal / Q000378:metabolism; D011736:Pyridoxine / Q000378:metabolism; D013489:Suppression, Genetic; D013696:Temperature
chemical_list: D010457:Peptidoglycan; D011730:Pyridoxal; D000591:Amino Acid Isomerases; D000411:Alanine Racemase; D011736:Pyridoxine; D000409:Alanine