Structure and function ofdnaQ andmutD mutators ofEscherichia coli
- 103 Downloads
The nucleotide sequences of the recessivednaQ49 and the dominantmutD5 mutator were determined. ThednaQ49 mutator has a single base substitution in thednaQ gene, thus causing one amino acid change,96Val (GTG)→ Gly (GGG), in the DnaQ protein (ε subunit of DNA polymerase III holoenzyme). ThemutD5 mutator possesses two base substitutions in the same gene, resulting in two amino acid changes,73Leu (TTG)→Trp (TGG) and164Ala (GCA)→Val (GTA), which were designated themutD52 andmutD51 mutations, respectively. Construction of chimaeric genes carrying one or two of these mutations revealed: (1) eithermutD51 ormutD52 alone causes the dominant mutator phenotype when present in a multi-copy plasmid; (2)mutD51, but notmutD52, exerts the dominant mutator phenotype when present in a low-copy plasmid; (3) the dominantmutD51 mutator activity is suppressed by thednaQ49 mutation when both mutations are present in the same gene. Based on these findings, we devised a model for the action of these mutators.
Key wordsMutator DNA polymerase III dnaQ gene Suppression
Unable to display preview. Download preview PDF.
- Maniatis T, Fritsch EF, Sambrook J (1982) Molecular cloning. A laboratory manual. Cold Spring Harbor Laboratory Press, Cold Spring Harbor, New YorkGoogle Scholar
- Sekiguchi M, Horiuchi T, Maki H, Maruyama M, Oeda K (1982) Cloning of mutator genes and identification of their products. In: Miwa M, Nishimura S, Rich A, Soll DG, Sugimura T (eds) Primary and tertiary structure of nucleic acids and cancer research. Japan Scientific Societies Press, Tokyo, pp 181–188Google Scholar