title: Temperature-dependent conjugative transfer of R27: role of chromosome- and plasmid-encoded Hha and H-NS proteins.
abstract: IncHI plasmids encode multiple-antibiotic resistance in Salmonella enterica serovar Typhi. These plasmids have been considered to play a relevant role in the persistence and reemergence of this microorganism. The IncHI1 plasmid R27, which can be considered the prototype of IncHI plasmids, is thermosensitive for transfer. Conjugation frequency is highest at low temperature (25 to 30 degrees C), decreasing when temperature increases. R27 codifies an H-NS-like protein (open reading frame 164 [ORF164]) and an Hha-like protein (ORF182). The H-NS and Hha proteins participate in the thermoregulation of gene expression in Escherichia coli. Here we investigated the hypothetical role of such proteins in thermoregulation of R27 conjugation. At a nonpermissive temperature (33 degrees C), transcription of several ORFs in both transfer region 1 (Tra1) and Tra2 from R27 is upregulated in cells depleted of Hha-like and H-NS-like proteins. Both chromosome- and plasmid-encoded Hha and H-NS proteins appear to potentially modulate R27 transfer. The function of R27-encoded Hha-like and H-NS proteins is not restricted to modulation of R27 transfer. Different mutant phenotypes associated with both chromosomal hha and hns mutations are compensated in cells harboring R27.
authors.affiliation: Departament de Microbiologia, Facultat de Biologia, Universitat de Barcelona, Avda. Diagonal 645, 08028 Barcelona, Spain.
authors.forename: Núria
authors.initials: N
authors.lastname: Forns
authors.forename: Rosa C
authors.initials: RC
authors.lastname: Baños
authors.forename: Carlos
authors.initials: C
authors.lastname: Balsalobre
authors.forename: Antonio
authors.initials: A
authors.lastname: Juárez
authors.forename: Cristina
authors.initials: C
authors.lastname: Madrid
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000502:physiology; D002876:Chromosomes, Bacterial / Q000235:genetics / Q000502:physiology*; D003227:Conjugation, Genetic / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000502:physiology; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000502:physiology*; D009154:Mutation; D010957:Plasmids / Q000235:genetics / Q000502:physiology*; D017386:Sequence Homology, Amino Acid; D013696:Temperature; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C031908:H-NS protein, bacteria; C079209:hha protein, E coli