Enrichment and elimination of mutY mutators in Escherichia coli populations.

Genetics

School of Molecular and Microbial Biosciences, University of Sydney, New South Wales 2006, Australia.

Published: November 2002

The kinetics of mutator sweeps was followed in two independent populations of Escherichia coli grown for up to 350 generations in glucose-limited continuous culture. A rapid elevation of mutation rates was observed in both populations within 120-150 generations, as was apparent from major increases in the proportion of the populations with unselected mutations in fhuA. The increase in mutation rates was due to sweeps by mutY mutators. In both cultures, the enrichment of mutators resulted from hitchhiking with identified beneficial mutations increasing fitness under glucose limitation; mutY hitchhiked with mgl mutations in one culture and ptsG in the other. In both cases, mutators were enriched to constitute close to 100% of the population before a periodic selection event reduced the frequency of unselected mutations and mutators in the cultures. The high proportion of mutators persisted for 150 generations in one population but began to be eliminated within 50 generations in the other. The persistence of mutator, as well as experimental data showing that mutY bacteria were as fit as near-isogenic mutY(+) bacteria in competition experiments, suggest that mutator load by deleterious mutations did not explain the rapidly diminishing proportion of mutators in the populations. The nonmutators sweeping out mutators were also unlikely to have arisen by reversion or antimutator mutations; the mutY mutations were major deletions in each case and the bacteria sweeping out mutators contained intact mutY. By following mgl allele frequencies in one population, we discovered that mutators were outcompeted by bacteria that had rare mgl mutations previously as well as additional beneficial mutation(s). The pattern of appearance of mutY, but not its elimination, conforms to current models of mutator sweeps in bacterial populations. A mutator with a narrow mutational spectrum like mutY may be lost if the requirement for beneficial mutations is for changes other than GC --> TA transversions. Alternatively, epistatic interactions between mutator mutation and beneficial mutations need to be postulated to explain mutator elimination.

Download full-text PDF

Source
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1462320PMC
http://dx.doi.org/10.1093/genetics/162.3.1055DOI Listing

Publication Analysis

Top Keywords

beneficial mutations
16
mutations
11
mutators
10
muty
8
muty mutators
8
escherichia coli
8
mutator sweeps
8
mutation rates
8
unselected mutations
8
mutators cultures
8

Similar Publications

The cultivation of opium poppy is the only commercially viable source of most morphinan alkaloids. Bioproduction of morphinan alkaloids in recombinant whole-cell systems provides a promising alternate source of these valuable compounds. The enzyme codeine 3-O-demethylase can transform morphinan alkaloids by O-demethylation and has been applied in single step biotransformation reactions or as part of larger biosynthetic cascade, however, the productivity for these reactions remains low and suboptimal enzyme properties could be improved.

View Article and Find Full Text PDF

Structural variants of AcrIIC5 inhibit Cas9 via divergent binding interfaces.

Structure

January 2025

Department of Agricultural Biotechnology, Seoul National University, Seoul 08826, South Korea; Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul 08826, South Korea. Electronic address:

CRISPR-Cas is a bacterial defense system that employs RNA-guided endonucleases to destroy invading foreign nucleic acids. Bacteriophages produce anti-CRISPR (Acr) proteins to evade CRISPR-Cas defense during the infection. AcrIIC5, a type II-C Cas9 inhibitor, exhibits unusual variations in the local backbone fold between its orthologs.

View Article and Find Full Text PDF

Sex disparities in the association between rare earth elements exposure and genetic mutation frequencies in lung cancer patients.

Sci Rep

January 2025

Department of Oncology, Senior Department of Respiratory and Critical Care Medicine, The Eighth Medical Center of Chinese PLA General Hospital, No.17 A Heishanhu Road, Haidian District, Beijing, 100853, China.

The ubiquitous use of rare earth elements (REEs) in modern living environments raised concern about their impact on human health. With the detrimental and beneficial effects of REEs reported by different studies, the genuine role of REEs in the human body remains a mystery. This study explored the association between REEs and genetic mutations in patients with lung adenocarcinoma (LUAD).

View Article and Find Full Text PDF

Congenital muscular dystrophies and myopathies: the leading cause of genetic muscular disorders in eleven Chinese families.

BMC Musculoskelet Disord

January 2025

Medical Genetic Diagnosis and Therapy Center, Fujian Maternity and Child Health Hospital, College of Clinical Medicine for Obstetrics and Gynecology and Pediatrics, Fujian Medical University, 18 Daoshan Road, Fuzhou, 350001, China.

Background: Congenital muscular dystrophies (CMDs) and myopathies (CMYOs) are a clinically and genetically heterogeneous group of neuromuscular disorders that share common features, such as muscle weakness, hypotonia, characteristic changes on muscle biopsy and motor retardation. In this study, we recruited eleven families with early-onset neuromuscular disorders in China, aimed to clarify the underlying genetic etiology.

Methods: Essential clinical tests, such as biomedical examination, electromyography and muscle biopsy, were applied to evaluate patient phenotypes.

View Article and Find Full Text PDF

Want AI Summaries of new PubMed Abstracts delivered to your In-box?

Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!