title: A novel component of the Rhodobacter sphaeroides Fla1 flagellum is essential for motor rotation.
abstract: Here we describe a novel component essential for flagellar rotation in Rhodobacter sphaeroides. This protein is encoded by motF (RSP_0067), the first gene of a predicted transcriptional unit which contains two hypothetical genes. Sequence analysis indicated that MotF is a bitopic membrane-spanning protein. Protease sensitivity assays and green fluorescent protein (GFP) fusions confirmed this prediction and allowed us to conclude that the C terminus of MotF is located in the periplasmic space. Wild-type cells expressing a functional GFP-MotF fusion show a single fluorescent focus per cell. The localization of this protein in different genetic backgrounds allowed us to determine that normal localization of MotF depends on the presence of FliL and MotB. Characterization of a ΔmotF pseudorevertant strain revealed that a single nucleotide change in motB suppresses the Mot(-) phenotype of the motF mutant. Additionally, we show that MotF also becomes dispensable when other mutant alleles of motB previously isolated as second-site suppressors of ΔfliL were expressed in the motF mutant strain. These results show that MotF is a new component of the Fla1 flagellum, which together with FliL is required to promote flagellar rotation, possibly through MotB.
authors.affiliation: Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico.
authors.forename: Victor
authors.initials: V
authors.lastname: Ramírez-Cabrera
authors.forename: Sebastian
authors.initials: S
authors.lastname: Poggio
authors.forename: Clelia
authors.initials: C
authors.lastname: Domenzain
authors.forename: Aurora
authors.initials: A
authors.lastname: Osorio
authors.forename: Georges
authors.initials: G
authors.lastname: Dreyfus
authors.forename: Laura
authors.initials: L
authors.lastname: Camarena
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000907:Antibodies, Bacterial; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D005260:Female; D005407:Flagella / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D020409:Molecular Motor Proteins / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D019897:Periplasm; D010957:Plasmids; D017354:Point Mutation; D012242:Rhodobacter sphaeroides / Q000235:genetics / Q000378:metabolism*
chemical_list: D000907:Antibodies, Bacterial; D001426:Bacterial Proteins; D008565:Membrane Proteins; D020409:Molecular Motor Proteins