sigma(54) Promoters control expression of genes encoding the hook and basal body complex in Rhodobacter sphaeroides.
Gene expression of the flagellar system is tightly controlled by external stimuli or intracellular signals. A general picture of this regulation has been obtained from studies of Salmonella enterica serovar Typhimurium. However, these regulatory mechanisms do not apply to all bacterial groups. In this study, we have investigated regulation of the flagellar genetic system in Rhodobacter sphaeroides. Deletion analysis, site-directed mutagenesis, and 5'-end mapping were conducted in order to identify the fliO promoter. Our results indicate that this promoter is recognized by the factor sigma(54). Additionally, 5'-end mapping of the flgB and fliK transcripts suggests that these mRNAs are also transcribed from sigma(54) promoters. Finally, we showed evidence that suggests that fliC transcription is not entirely dependent on the presence of a complete basal body-hook structure. Our results are discussed in the context of a possible regulatory hierarchy controlling flagellar gene expression in R. sphaeroides.
Poggio
S
S
Departamento de Biología Molecular, Instituto de Investigaciones Biomédicas, 04510 Mexico City, Mexico.
Aguilar
C
C
Osorio
A
A
González-Pedrajo
B
B
Dreyfus
G
G
Camarena
L
L
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D004268:DNA-Binding Proteins; D012321:DNA-Directed RNA Polymerases / Q000235:genetics* / Q000378:metabolism; D005407:Flagella / Q000235:genetics*; D005408:Flagellin / Q000737:chemistry / Q000235:genetics; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D005966:Glucuronidase / Q000235:genetics; D008565:Membrane Proteins; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011401:Promoter Regions, Genetic; D051877:RNA Polymerase Sigma 54; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D012242:Rhodobacter sphaeroides / Q000166:cytology / Q000235:genetics*; D012808:Sigma Factor / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; C099486:FliK protein, Bacteria; C085247:FliO protein, Bacteria; D008565:Membrane Proteins; D011993:Recombinant Fusion Proteins; D012808:Sigma Factor; D005408:Flagellin; D012321:DNA-Directed RNA Polymerases; D051877:RNA Polymerase Sigma 54; D005966:Glucuronidase