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Titolo:
THE ESCHERICHIA-COLI GALK2 PAPILLATION ASSAY - ITS SPECIFICITY AND APPLICATION TO 7 NEWLY ISOLATED MUTATOR STRAINS
Autore:
OLLER AR; FIJALKOWSKA IJ; SCHAAPER RM;
Indirizzi:
NIEHS,MOLEC GENET LAB,POB 12233,111 TW ALEXANDER DR RES TRIANGLE PK NC 27709 NIEHS,MOLEC GENET LAB,POB 12233,111 TW ALEXANDER DR RES TRIANGLE PK NC 27709
Titolo Testata:
MUTATION RESEARCH
fascicolo: 2, volume: 292, anno: 1993,
pagine: 175 - 185
SICI:
0027-5107(1993)292:2<175:TEGPA->2.0.ZU;2-D
Fonte:
ISI
Lingua:
ENG
Soggetto:
DNA POLYMERASE-III; MISMATCH REPAIR; MUTD5; MUTAGENESIS; GENE; MUTANTS; REPLICATION; SATURATION; HOLOENZYME; MECHANISMS;
Keywords:
GALK2 GENE; PAPILLATION ASSAY; ESCHERICHIA-COLI MUTATOR STRAINS; DNA POLYMERASE; EXONUCLEOLYTIC PROOFREADING; DNAE GENE; DNAQ GENE;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
41
Recensione:
Indirizzi per estratti:
Citazione:
A.R. Oller et al., "THE ESCHERICHIA-COLI GALK2 PAPILLATION ASSAY - ITS SPECIFICITY AND APPLICATION TO 7 NEWLY ISOLATED MUTATOR STRAINS", MUTATION RESEARCH, 292(2), 1993, pp. 175-185

Abstract

The Escherichia coli dnaE and dnaQ genes encode, respectively, the alpha (polymerase) and epsilon (proofreading) subunits of DNA polymeraseIII. Mutations in these genes resulting in mutator or antimutator phenotypes provide important tools to understand the mechanisms by which mutations occur. One way to isolate such strains is the use of papillation assays. We used one such assay based on the reversion of the galK2 allele in cells grown on MacConkey-Gal plates. Here, we describe theidentification of the galK2 mutation and its possible reversion pathways, and the characterization of 7 mutators isolated using this system. 1 mutator resided in dnaE and 6 in dnaQ. Sequencing of the galK2 allele revealed a G . C --> T . A transversion at base pair 571 that changed a glu codon (GAA) to a stop codon (TAA). The analysis of 319 revertants showed that a Gal+ phenotype can be achieved by A . T --> G . C transition, A . T --> T . A transversion and A . T --> C . G transversion. We characterized the mutator phenotypes of the newly isolated mutators by determining (i) their mutation frequencies to resistance to rifampicin and nalidixic acid in both wild-type and mutL backgrounds, (ii) their temperature sensitivity and medium dependence and (iii) their mutational specificity (by analyzing the nature of galK revertants). Based on the genomic locations of their mutations, specificity of reversion pathways and magnitude of mutator effects, the mutators can be grouped into 3 classes. These classes may represent different mutational mechanisms that include defective base insertion, defective proofreading and interference with the postreplicative mismatch-repair system.

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Documento generato il 19/09/20 alle ore 08:03:58