title: Inhibiting translation elongation can aid genome duplication in Escherichia coli.
abstract: Conflicts between replication and transcription challenge chromosome duplication. Escherichia coli replisome movement along transcribed DNA is promoted by Rep and UvrD accessory helicases with Δrep ΔuvrD cells being inviable under rapid growth conditions. We have discovered that mutations in a tRNA gene, aspT, in an aminoacyl tRNA synthetase, AspRS, and in a translation factor needed for efficient proline-proline bond formation, EF-P, suppress Δrep ΔuvrD lethality. Thus replication-transcription conflicts can be alleviated by the partial sacrifice of a mechanism that reduces replicative barriers, namely translating ribosomes that reduce RNA polymerase backtracking. Suppression depends on RelA-directed synthesis of (p)ppGpp, a signalling molecule that reduces replication-transcription conflicts, with RelA activation requiring ribosomal pausing. Levels of (p)ppGpp in these suppressors also correlate inversely with the need for Rho activity, an RNA translocase that can bind to emerging transcripts and displace transcription complexes. These data illustrate the fine balance between different mechanisms in facilitating gene expression and genome duplication and demonstrate that accessory helicases are a major determinant of this balance. This balance is also critical for other aspects of bacterial survival: the mutations identified here increase persistence indicating that similar mutations could arise in naturally occurring bacterial populations facing antibiotic challenge.
authors.affiliation: Department of Biology, University of York, Wentworth Way, York YO10 5DD, UK.
authors.forename: Kamila K
authors.initials: KK
authors.lastname: Myka
authors.affiliation: Department of Biology, University of York, Wentworth Way, York YO10 5DD, UK.
authors.forename: Michelle
authors.initials: M
authors.lastname: Hawkins
authors.affiliation: Department of Biology, University of York, Wentworth Way, York YO10 5DD, UK.
authors.forename: Aisha H
authors.initials: AH
authors.lastname: Syeda
authors.affiliation: School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Aberdeen AB25 2ZD, UK.
authors.forename: Milind K
authors.initials: MK
authors.lastname: Gupta
authors.affiliation: Institute for Global Food Security, Queen's University Belfast, David Keir Building, Malone Road, Belfast BT9 5BN, UK.
authors.forename: Caroline
authors.initials: C
authors.lastname: Meharg
authors.affiliation: DNA-Protein Interactions Unit, School of Biochemistry, University of Bristol, Bristol BS8, 1TD, UK.
authors.forename: Mark S
authors.initials: MS
authors.lastname: Dillingham
authors.affiliation: DNA-Protein Interactions Unit, School of Biochemistry, University of Bristol, Bristol BS8, 1TD, UK.
authors.forename: Nigel J
authors.initials: NJ
authors.lastname: Savery
authors.affiliation: Centre for Genetics and Genomics, University of Nottingham, Queen's Medical Centre, Nottingham NG7 2UH, UK.
authors.forename: Robert G
authors.initials: RG
authors.lastname: Lloyd
authors.affiliation: Department of Biology, University of York, Wentworth Way, York YO10 5DD, UK.
authors.forename: Peter
authors.initials: P
authors.lastname: McGlynn
mesh_terms: D004265:DNA Helicases / Q000235:genetics; D004261:DNA Replication; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism; D016680:Genome, Bacterial; D009154:Mutation; D010441:Peptide Chain Elongation, Translational; D012349:RNA, Transfer, Asp / Q000235:genetics; D013489:Suppression, Genetic; D046249:Transfer RNA Aminoacylation
chemical_list: D029968:Escherichia coli Proteins; D012349:RNA, Transfer, Asp; C534627:Rho protein, E coli; C506744:rep protein, E coli; C506746:UvrD protein, E coli; D004265:DNA Helicases