title: [Studies of gene regulation of de novo biosynthetic pathway of purine in Salmonella typhimurium. X. Isolation of purR(am) mutants and preliminary studies of amino acid substitution].
abstract: Starting from a super-repressed mutant of purR, 3-18, 439 independent candidates of purR- mutants were isolated by using NCE selecting plate with lactose as sole carbon source. Among these mutants. 11 amber mutants were detected by introducing a tRNA suppressor gene. Cotransduction analysis proved that the amber mutation sites of 11 amber mutants all located on purR. Amino acid substitution experiments were performed with three tRNA suppressors, supD, supE and supF, for each purR(am). The results showed that the same amino acid substitution occurred in different site of PurR protein could result in varied effects on purR function; different amino acid substitution occurred at the same position of PurR protein also could produced varied effects on purR function.
authors.affiliation: Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.
authors.forename: H S
authors.initials: HS
authors.lastname: Zhang
authors.forename: A Q
authors.initials: AQ
authors.lastname: Wang
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000502:physiology; D009154:Mutation; D011687:Purines / Q000096:biosynthesis*; D012097:Repressor Proteins / Q000737:chemistry* / Q000502:physiology; D012486:Salmonella typhimurium / Q000235:genetics*; D013329:Structure-Activity Relationship
chemical_list: D001426:Bacterial Proteins; C065825:PurR protein, Bacteria; D011687:Purines; D012097:Repressor Proteins