title: Antimicrobial Susceptibility and SOS-Dependent Increase in Mutation Frequency Are Impacted by Escherichia coli Topoisomerase I C-Terminal Point Mutation.
abstract: Topoisomerase functions are required in all organisms for many vital cellular processes, including transcription elongation. The C terminus domains (CTD) of Escherichia coli topoisomerase I interact directly with RNA polymerase to remove transcription-driven negative supercoiling behind the RNA polymerase complex. This interaction prevents inhibition of transcription elongation from hypernegative supercoiling and R-loop accumulation. The physiological function of bacterial topoisomerase I in transcription is especially important for a rapid network response to an antibiotic challenge. In this study, Escherichia coli with a topA66 single nucleotide deletion mutation, which results in a frameshift in the TopA CTD, was shown to exhibit increased sensitivity to trimethoprim and quinolone antimicrobials. The topoisomerase I-RNA polymerase interaction and the SOS response to the antimicrobial agents were found to be significantly reduced by this topA66 mutation. Consequently, the mutation frequency measured by rifampin selection following SOS induction was diminished in the topA66 mutant. The increased antibiotic sensitivity for the topA66 mutant can be reversed by the expression of recombinant E. coli topoisomerase I but not by the expression of recombinant Mycobacterium tuberculosis topoisomerase I that has a nonhomologous CTD even though the recombinant M. tuberculosis topoisomerase I can restore most of the plasmid DNA linking number deficiency caused by the topA66 mutation. Direct interactions of E. coli topoisomerase I as part of transcription complexes are likely to be required for the rapid network response to an antibiotic challenge. Inhibitors of bacterial topoisomerase I functions and interactions may sensitize pathogens to antibiotic treatment and limit the mutagenic response.
authors.affiliation: Department of Biochemistry and Molecular Biology, New York Medical College, Valhalla, New York, USA.
authors.forename: Jenny
authors.initials: J
authors.lastname: Yang
authors.affiliation: Department of Chemistry and Biochemistry, Florida International University, Miami, Florida, USA.
authors.forename: Thirunavukkarasu
authors.initials: T
authors.lastname: Annamalai
authors.affiliation: Department of Biochemistry and Molecular Biology, New York Medical College, Valhalla, New York, USA.
authors.forename: Bokun
authors.initials: B
authors.lastname: Cheng
authors.affiliation: Department of Chemistry and Biochemistry, Florida International University, Miami, Florida, USA.
authors.forename: Srikanth
authors.initials: S
authors.lastname: Banda
authors.affiliation: Department of Biochemistry and Molecular Biology, New York Medical College, Valhalla, New York, USA.
authors.forename: Rakhi
authors.initials: R
authors.lastname: Tyagi
authors.affiliation: Department of Chemistry and Biochemistry, Florida International University, Miami, Florida, USA Biomolecular Sciences Institute, Florida International University, Miami, Florida, USA yukching.tsedinh@fiu.edu.
authors.forename: Yuk-Ching
authors.initials: YC
authors.lastname: Tse-Dinh
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D004264:DNA Topoisomerases, Type I / Q000235:genetics* / Q000378:metabolism; D012321:DNA-Directed RNA Polymerases / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000235:genetics* / Q000378:metabolism; D016368:Frameshift Mutation; D015964:Gene Expression Regulation, Bacterial; D005816:Genetic Complementation Test; D008826:Microbial Sensitivity Tests; D059645:Mutation Rate; D009169:Mycobacterium tuberculosis / Q000737:chemistry; D010957:Plasmids / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D015363:Quinolones / Q000494:pharmacology; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012293:Rifampin / Q000494:pharmacology; D013014:SOS Response, Genetics / Q000187:drug effects; D061805:Transcription Elongation, Genetic; D014295:Trimethoprim / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D029968:Escherichia coli Proteins; D015363:Quinolones; D011994:Recombinant Proteins; D014295:Trimethoprim; D012321:DNA-Directed RNA Polymerases; D004264:DNA Topoisomerases, Type I; D012293:Rifampin