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Functions that Protect Escherichia coli from Tightly Bound DNA-Protein Complexes Created by Mutant EcoRII Methyltransferase.

Publication ,  Journal Article
Henderson, ML; Kreuzer, KN
Published in: PLoS One
2015

Expression of mutant EcoRII methyltransferase protein (M.EcoRII-C186A) in Escherichia coli leads to tightly bound DNA-protein complexes (TBCs), located sporadically on the chromosome rather than in tandem arrays. The mechanisms behind the lethality induced by such sporadic TBCs are not well studied, nor is it clear whether very tight binding but non-covalent complexes are processed in the same way as covalent DNA-protein crosslinks (DPCs). Using 2D gel electrophoresis, we found that TBCs induced by M.EcoRII-C186A block replication forks in vivo. Specific bubble molecules were detected as spots on the 2D gel, only when M.EcoRII-C186A was induced, and a mutation that eliminates a specific EcoRII methylation site led to disappearance of the corresponding spot. We also performed a candidate gene screen for mutants that are hypersensitive to TBCs induced by M.EcoRII-C186A. We found several gene products necessary for protection against these TBCs that are known to also protect against DPCs induced with wild-type M.EcoRII (after 5-azacytidine incorporation): RecA, RecBC, RecG, RuvABC, UvrD, FtsK, XerCD and SsrA (tmRNA). In contrast, the RecFOR pathway and Rep helicase are needed for protection against TBCs but not DPCs induced by M.EcoRII. We propose that stalled fork processing by RecFOR and RecA promotes release of tightly bound (but non-covalent) blocking proteins, perhaps by licensing Rep helicase-driven dissociation of the blocking M.EcoRII-C186A. Our studies also argued against the involvement of several proteins that might be expected to protect against TBCs. We took the opportunity to directly compare the sensitivity of all tested mutants to two quinolone antibiotics, which target bacterial type II topoisomerases and induce a unique form of DPC. We uncovered rep, ftsK and xerCD as novel quinolone hypersensitive mutants, and also obtained evidence against the involvement of a number of functions that might be expected to protect against quinolones.

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Published In

PLoS One

DOI

EISSN

1932-6203

Publication Date

2015

Volume

10

Issue

5

Start / End Page

e0128092

Location

United States

Related Subject Headings

  • Recombination, Genetic
  • Quinolones
  • Mutation
  • General Science & Technology
  • Escherichia coli Proteins
  • Escherichia coli
  • DNA-Cytosine Methylases
  • DNA, Bacterial
  • DNA Replication
  • Chromosomes, Bacterial
 

Citation

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Henderson, M. L., & Kreuzer, K. N. (2015). Functions that Protect Escherichia coli from Tightly Bound DNA-Protein Complexes Created by Mutant EcoRII Methyltransferase. PLoS One, 10(5), e0128092. https://doi.org/10.1371/journal.pone.0128092
Henderson, Morgan L., and Kenneth N. Kreuzer. “Functions that Protect Escherichia coli from Tightly Bound DNA-Protein Complexes Created by Mutant EcoRII Methyltransferase.PLoS One 10, no. 5 (2015): e0128092. https://doi.org/10.1371/journal.pone.0128092.
Henderson, Morgan L., and Kenneth N. Kreuzer. “Functions that Protect Escherichia coli from Tightly Bound DNA-Protein Complexes Created by Mutant EcoRII Methyltransferase.PLoS One, vol. 10, no. 5, 2015, p. e0128092. Pubmed, doi:10.1371/journal.pone.0128092.

Published In

PLoS One

DOI

EISSN

1932-6203

Publication Date

2015

Volume

10

Issue

5

Start / End Page

e0128092

Location

United States

Related Subject Headings

  • Recombination, Genetic
  • Quinolones
  • Mutation
  • General Science & Technology
  • Escherichia coli Proteins
  • Escherichia coli
  • DNA-Cytosine Methylases
  • DNA, Bacterial
  • DNA Replication
  • Chromosomes, Bacterial