Altered nutritional requirements associated with mutations affecting the structures of ribonucleic acid polymerase in Lactobacillus casei.
Rifampin-resistant mutants were isolated from Lactobacillus casei S1 and examined for possible simultaneous alteration in nutritional properties. Among the 36 mutants obtained either spontaneously or after mutagenesis with 2-aminopurine, 22 were found to be altered with respect to the specific growth requirements. The majority (20 of 22) of the latter mutants were shown to require L-glutamine in addition to the nutrients required by the parental strain for maximal growth, whereas the remaining mutants had apparently lost the requirement for L-aspartate. Further studies with one of the glutamine-requiring mutants revealed that the rifampin resistance of this strain is due to the resistance of ribonucleic acid polymerase itself and that a single mutation is responsible for both rifampin resistance and the glutamine requirement. These results strongly indicate that a structural alteration of the ribonucleic acid polymerase caused by the rifampin resistance mutation somehow affected glutamine metabolism, possibly through change in selective transcription of the genes involved.
D015075:2-Aminopurine; D050260:Carbohydrate Metabolism; D002474:Cell-Free System; D012321:DNA-Directed RNA Polymerases / Q000096:biosynthesis* / Q000378:metabolism; D004352:Drug Resistance, Microbial; D005285:Fermentation; D005974:Glutamate-Ammonia Ligase / Q000378:metabolism; D005973:Glutamine / Q000378:metabolism; D007780:Lacticaseibacillus casei / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D009153:Mutagens; D009154:Mutation; D012293:Rifampin / Q000494:pharmacology; D013237:Stereoisomerism
D009153:Mutagens; D005973:Glutamine; D015075:2-Aminopurine; D012321:DNA-Directed RNA Polymerases; D005974:Glutamate-Ammonia Ligase; D012293:Rifampin