title: Escherichia coli gene purR encoding a repressor protein for purine nucleotide synthesis. Cloning, nucleotide sequence, and interaction with the purF operator.
abstract: The Escherichia coli gene purR, encoding a repressor protein, was cloned by complementation of a purR mutation. Gene purR on a multicopy plasmid repressed expression of purF and purF-lacZ and reduced the growth rate of host cells by limiting the rate of de novo purine nucleotide synthesis. The level of a 1.3-kilobase purR mRNA was higher in cells grown with excess adenine, suggesting that synthesis of the repressor may be regulated. The chromosomal locus of purR was mapped to coordinate 1755-kb on the E. coli restriction map (Kohara, Y., Akiyama, K., and Isono, K. (1987) Cell 50, 495-508). Pur repressor bound specifically to purF operator DNA as determined by gel retardation and DNase I footprinting assays. The amino acid sequence of Pur repressor was derived from the nucleotide sequence. Pur repressor subunit contains 341 amino acids and has a calculated Mr of 38,179. Pur repressor is 31-35% identical with the galR and cytR repressors and 26% identical with the lacI repressor. These four repressors are likely homologous. Amino acid sequence similarity is greatest in an amino-terminal region presumed to contain a DNA-binding domain. A similarity is also noted in the operator sites for these repressors.
authors.affiliation: Department of Biochemistry, Purdue University, West Lafayette, Indiana 47907.
authors.forename: R J
authors.initials: RJ
authors.lastname: Rolfes
authors.forename: H
authors.initials: H
authors.lastname: Zalkin
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics* / Q000254:growth & development; D005796:Genes; D005798:Genes, Bacterial; D005816:Genetic Complementation Test; D005838:Genotype; D008969:Molecular Sequence Data; D009876:Operon; D010957:Plasmids; D011685:Purine Nucleotides / Q000096:biosynthesis*; D012097:Repressor Proteins / Q000235:genetics*; D015183:Restriction Mapping; D012689:Sequence Homology, Nucleic Acid; D014157:Transcription Factors / Q000235:genetics*
chemical_list: D011685:Purine Nucleotides; D012097:Repressor Proteins; D014157:Transcription Factors