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Escherichia coli parA is an allele of the gyrB gene
J Kato1, Y Nishimura, H Suzuki
1Laboratory of Genetics, Department of Biology, Faculty of Science, University of Tokyo, Japan.
Abstract:
A thermosensitive (ts) parA mutant, MFT110, of Escherichia coli carried at least two ts mutations. The major ts defect, resulting from a mutation mapped originally at 95 min and complemented by pLC8-47, was most probably due to psd. A plasmid carrying the 1.6 kb BamHI-PvuII fragment recloned from pLC8-47 complemented the major ts mutation in MFT110 and psd(ts) in two mutants, but did not correct the Par phenotype of MFT110. The second ts mutation was salt-repairable and mapped at 83 min close to recF and tnaA. This mutation was linked with the Par phenotype as shown unambiguously by 4',6-diamidino-2-phenylindole stained nucleoids in parA mutant cells with the W3110 genetic background. Both salt-repairable ts and Par traits were corrected concomitantly by a plasmid carrying the chromosomal region solely for the gyrB gene. This strongly suggests that parA is an allele of gyrB.
Insights
This study identifies a second thermosensitive mutation in Escherichia coli parA mutants. This mutation, linked to the Par phenotype, is likely an allele of the gyrB gene.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Thermosensitive (ts) mutations are valuable tools for studying essential genes.
- The parA locus in Escherichia coli is involved in cell division and chromosome segregation.
Purpose of the Study:
- To characterize the genetic basis of thermosensitivity and the Par phenotype in an Escherichia coli parA mutant (MFT110).
- To identify the specific gene(s) responsible for the observed mutations.
Main Methods:
- Genetic mapping of thermosensitive mutations.
- Complementation analysis using plasmids carrying specific gene fragments.
- Phenotypic analysis of nucleoids using 4',6-diamidino-2-phenylindole staining.
- Assessment of salt-repairable traits.
Main Results:
- MFT110 exhibited at least two ts mutations; one likely involved psd, while the second was salt-repairable and mapped near recF and tnaA.
- The salt-repairable ts mutation was linked to the Par phenotype.
- A plasmid containing the gyrB gene corrected both the salt-repairable ts defect and the Par phenotype.
Conclusions:
- The parA locus in Escherichia coli contains a mutation that is likely an allele of the gyrB gene.
- GyrB plays a crucial role in maintaining cell division and chromosome segregation under non-permissive conditions.