title: Regulation of finP transcription by DNA adenine methylation in the virulence plasmid of Salmonella enterica.
abstract: DNA adenine methylase (Dam(-)) mutants of Salmonella enterica serovar Typhimurium contain reduced levels of FinP RNA encoded on the virulence plasmid. Dam methylation appears to regulate finP transcription, rather than FinP RNA stability or turnover. The finP promoter includes canonical -10 and -35 modules and depends on the sigma(70) factor. Regulation of finP transcription by Dam methylation does not require DNA sequences upstream from the -35 module, indicating that Dam acts at the promoter itself or downstream. Unexpectedly, a GATC site overlapping with the -10 module is likewise dispensable for Dam-mediated regulation. These observations indicate that Dam methylation regulates finP transcription indirectly and suggest the involvement of a host factor(s) responsive to the Dam methylation state of the cell. We provide evidence that one such factor is the nucleoid protein H-NS, which acts as a repressor of finP transcription in a Dam(-) background. H-NS also restrains transcription of the overlapping traJ gene, albeit in a Dam-independent fashion. Hence, the decreased FinP RNA content found in Dam(-) hosts of S. enterica appears to result from H-NS-mediated repression of finP transcription.
authors.affiliation: Departamento de Genética, Facultad de Biología, Universidad de Sevilla, Apartado 1095, E-41080 Sevilla, Spain.
authors.forename: Eva M
authors.initials: EM
authors.lastname: Camacho
authors.forename: Ana
authors.initials: A
authors.lastname: Serna
authors.forename: Cristina
authors.initials: C
authors.lastname: Madrid
authors.forename: Silvia
authors.initials: S
authors.lastname: Marqués
authors.forename: Raúl
authors.initials: R
authors.lastname: Fernández
authors.forename: Fernando
authors.initials: F
authors.lastname: de la Cruz
authors.forename: Antonio
authors.initials: A
authors.lastname: Juárez
authors.forename: Josep
authors.initials: J
authors.lastname: Casadesús
mesh_terms: D000225:Adenine / Q000378:metabolism; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D019175:DNA Methylation; D018628:Gene Dosage; D007763:Lac Operon; D016297:Mutagenesis, Site-Directed; D010957:Plasmids / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics; D012329:RNA, Bacterial / Q000235:genetics* / Q000378:metabolism; D022661:RNA, Untranslated / Q000235:genetics* / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D013014:SOS Response, Genetics / Q000502:physiology; D012486:Salmonella typhimurium / Q000235:genetics* / Q000378:metabolism* / Q000472:pathogenicity; D015265:Site-Specific DNA-Methyltransferase (Adenine-Specific) / Q000235:genetics / Q000378:metabolism; D024363:Transcription Initiation Site / Q000502:physiology; D014158:Transcription, Genetic / Q000502:physiology; D014774:Virulence
chemical_list: D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D012329:RNA, Bacterial; D022661:RNA, Untranslated; D011993:Recombinant Fusion Proteins; C041427:TraJ protein, bacteria; C058693:Dam methyltransferase; D015265:Site-Specific DNA-Methyltransferase (Adenine-Specific); D000225:Adenine