PMID:9705512
| Citation |
Taft-Benz, SA and Schaaper, RM (1998) Mutational analysis of the 3'-->5' proofreading exonuclease of Escherichia coli DNA polymerase III. Nucleic Acids Res. 26:4005-11 |
|---|---|
| Abstract |
The epsilon subunit of Escherichia coli DNA polymerase III holoenzyme, the enzyme primarily responsible for the duplication of the bacterial chromosome, is a 3'-->5' exonuclease that functions as a proofreader for polymerase errors. In addition, it plays an important structural role within the pol III core. To gain further insight into how epsilon performs these joint structural and catalytic functions, we have investigated a set of 20 newly isolated dnaQ mutator mutants. The mutator effects ranged from strong (700-8000-fold enhancement) to moderate (6-20-fold enhancement), reflecting the range of proofreading deficiencies. Complementation assays revealed most mutators to be partially or fully dominant, suggesting that they carried an exonucleolytic defect but retained binding to the pol III core subunits. One allele, containing a stop codon 3 amino acids from the C-terminal end of the protein, was fully recessive. Sequence analysis of the mutants revealed mutations in the Exo I, Exo II and recently proposed Exo IIIepsilon motifs, as well as in the intervening regions. Together, the data support the functional significance of the proposed motifs, presumably in catalysis, and suggest that the C-terminus of straightepsilon may be specifically involved in binding to the alpha (polymerase) subunit. |
| Links | |
| Keywords |
Amino Acid Sequence; Codon, Terminator; Conserved Sequence; DNA Mutational Analysis; DNA Polymerase III/genetics; DNA Replication/genetics; DNA, Bacterial/biosynthesis; Escherichia coli/enzymology; Escherichia coli/genetics; Escherichia coli Proteins; Exodeoxyribonuclease V; Exodeoxyribonucleases/genetics; Genetic Complementation Test; Mutagenesis/genetics; Sequence Analysis, DNA; Sequence Homology, Amino Acid |
| edit table |
Significance
You can help EcoliWiki by summarizing why this paper is useful
Useful Materials and Methods
You can help Ecoliwiki by describing the useful materials (strains, plasmids, antibodies, etc) described in this paper.
Annotations
<annotationlinks/>
EcoliWiki Links
Add links to pages that link here (e.g. gene, product, method pages)
References
See Help:References for how to manage references in EcoliWiki.