PMID:13129626
| Citation |
Trun, N (2003) Mutations in the E. coli Rep helicase increase the amount of DNA per cell. FEMS Microbiol. Lett. 226:187-93 |
|---|---|
| Abstract |
The mbrA4 mutation confers camphor resistance, severe growth defects and up to a two-fold increase in the amount of chromosomal DNA per cell. The extra DNA is replicated from oriC in a synchronous fashion. Cells containing mbrA4 are more resistant to X-rays, indicating that the extra DNA represents complete or nearly complete chromosomes. I report here that mbrA4 is an unusual allele of the leading strand DNA helicase, Rep. Eight independently isolated alleles of rep(mbrA) contain the same three changes in the rep gene: a G to A at position -44 from the start of the mRNA (+1); an opal stop at codon 142; and a glycine to serine at codon 414 (G414S). My data indicate that rep(mbrA4) is not a null mutation and that the third mutation, G414S, is necessary for camphor resistance, the phenotype associated with increased DNA content per cell. I also show that increase in DNA content does not lead to independently segregating chromosomes. |
| Links | |
| Keywords |
Adenosine Triphosphatases/genetics; Adenosine Triphosphatases/metabolism; Alleles; Amino Acid Substitution; Chromosome Mapping; Chromosomes, Bacterial/metabolism; Codon, Nonsense; Cyclic AMP/genetics; Cyclic AMP/metabolism; Cyclic AMP Receptor Protein/genetics; Cyclic AMP Receptor Protein/metabolism; DNA Helicases/genetics; DNA Helicases/metabolism; DNA Mutational Analysis; DNA, Bacterial/metabolism; Escherichia coli/genetics; Escherichia coli/metabolism; Escherichia coli Proteins; Gene Expression Regulation, Bacterial; Genes, Bacterial; Mutation, Missense; Point Mutation; Promoter Regions, Genetic; Recombination, Genetic; Sequence Analysis, DNA |
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