RRC ID 59063
Author Raghunathan N, Goswami S, Leela JK, Pandiyan A, Gowrishankar J.
Title A new role for Escherichia coli Dam DNA methylase in prevention of aberrant chromosomal replication.
Journal Nucleic Acids Res
Abstract The Dam DNA methylase of Escherichia coli is required for methyl-directed mismatch repair, regulation of chromosomal DNA replication initiation from oriC (which is DnaA-dependent), and regulation of gene expression. Here, we show that Dam suppresses aberrant oriC-independent chromosomal replication (also called constitutive stable DNA replication, or cSDR). Dam deficiency conferred cSDR and, in presence of additional mutations (Δtus, rpoB*35) that facilitate retrograde replication fork progression, rescued the lethality of ΔdnaA mutants. The DinG helicase was required for rescue of ΔdnaA inviability during cSDR. Viability of ΔdnaA dam derivatives was dependent on the mismatch repair proteins, since such viability was lost upon introduction of deletions in mutS, mutH or mutL; thus generation of double strand ends (DSEs) by MutHLS action appears to be required for cSDR in the dam mutant. On the other hand, another DSE-generating agent phleomycin was unable to rescue ΔdnaA lethality in dam+ derivatives (mutS+ or ΔmutS), but it could do so in the dam ΔmutS strain. These results point to a second role for Dam deficiency in cSDR. We propose that in Dam-deficient strains, there is an increased likelihood of reverse replication restart (towards oriC) following recombinational repair of DSEs on the chromosome.
Volume 47(11)
Pages 5698-5711
Published 2019-6-20
DOI 10.1093/nar/gkz242
PII 5430841
PMID 30957852
PMC PMC6582345
MeSH Alleles Bacterial Proteins / metabolism Chromosome Aberrations Chromosomes / genetics* DNA / metabolism DNA Repair* DNA Replication* DNA, Bacterial / metabolism DNA-Binding Proteins / metabolism Escherichia coli / enzymology* Escherichia coli / genetics Escherichia coli Proteins / metabolism Gene Dosage Gene Expression Regulation, Bacterial Mutation Phenotype Phleomycins / chemistry Recombination, Genetic Sequence Analysis, DNA Site-Specific DNA-Methyltransferase (Adenine-Specific) / genetics*
IF 11.147
Times Cited 5
Prokaryotes E. coli Keio collection ASKA library