title: Growth phase-dependent control of R27 conjugation is mediated by the interplay between the plasmid-encoded regulatory circuit TrhR/TrhY-HtdA and the cAMP regulon.
abstract: Plasmids of the incompatibility group HI1 (IncHI1) have been isolated from several Gram-negative pathogens and are associated with the spread of multidrug resistance. Their conjugation is tightly regulated and it is inhibited at temperatures higher than 30°C, indicating that conjugation occurs outside warm-blooded hosts. Using R27, the prototype of IncHI1 plasmids, we report that plasmid transfer efficiency in E. coli strongly depends on the physiological state of the donor cells. Conjugation frequency is high when cells are actively growing, dropping sharply when cells enter the stationary phase of growth. Accordingly, our transcriptomic assays show significant downregulation of numerous R27 genes during the stationary phase, including several tra (transfer) genes. Growth phase-dependent regulation of tra genes transcription is independent of H-NS, a silencer of horizontal gene transfer, and ppGpp and RpoS, regulators of the stationary phase, but highly dependent on the plasmid-encoded regulatory circuit TrhR/TrhY-HtdA. The metabolic sensor cAMP, whose synthesis is chromosomally encoded, is also involved in the growth phase regulation of R27 conjugation by modulating htdA expression. Our data suggest that the involvement of regulators encoded by both chromosome and plasmid are required for efficient physiological control of IncHI1 plasmid conjugation.
authors: Departament de Microbiologia, Universitat de Barcelona, Avda. Diagonal 643, Barcelona, 08028, Spain.
authors: Marta
authors: M
authors: Gibert
authors: Departament de Microbiologia, Universitat de Barcelona, Avda. Diagonal 643, Barcelona, 08028, Spain.
authors: Sonia
authors: S
authors: Paytubi
authors: Centre Nacional d'Anàlisi Genòmica (CNAG), Parc Científic de Barcelona, Baldiri Reixac 4, Barcelona, 08028, Spain.
authors: Sergi
authors: S
authors: Beltrán
authors: Departament de Microbiologia, Universitat de Barcelona, Avda. Diagonal 643, Barcelona, 08028, Spain.|Institut de Bioenginyeria de Catalunya (IBEC), Parc Científic de Barcelona, Baldiri Reixac 10, Barcelona, 08028, Spain.
authors: Antonio
authors: A
authors: Juárez
authors: Departament de Microbiologia, Universitat de Barcelona, Avda. Diagonal 643, Barcelona, 08028, Spain.
authors: Carlos
authors: C
authors: Balsalobre
authors: Departament de Microbiologia, Universitat de Barcelona, Avda. Diagonal 643, Barcelona, 08028, Spain.
authors: Cristina
authors: C
authors: Madrid
mesh_terms: D003227:Conjugation, Genetic; D000242:Cyclic AMP / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics* / Q000254:growth & development* / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D022761:Gene Transfer, Horizontal; D010957:Plasmids / Q000235:genetics* / Q000378:metabolism; D018085:Regulon
chemical_list: D029968:Escherichia coli Proteins; D000242:Cyclic AMP