title: Biochemical Characterization of the Flagellar Rod Components of Rhodobacter sphaeroides: Properties and Interactions.
abstract: The flagellar basal body is a rotary motor that spans the cytoplasmic and outer membranes. The rod is a drive shaft that transmits torque generated by the motor through the hook to the filament that propels the bacterial cell. The assembly and structure of the rod are poorly understood. In a first attempt to characterize this structure in the alphaproteobacterium Rhodobacter sphaeroides, we overexpressed and purified FliE and the four related rod proteins (FlgB, FlgC, FlgF, and FlgG), and we analyzed their ability to form homo-oligomers. We found that highly purified preparations of these proteins formed high-molecular-mass oligomers that tended to dissociate in the presence of NaCl. As predicted by in silico modeling, the four rod proteins share architectural features. Using affinity blotting, we detected the heteromeric interactions between these proteins. In addition, we observed that deletion of the N- and C-terminal regions of FlgF and FlgG severely affected heteromeric but not homomeric interactions. On the basis of our findings, we propose a model of rod assembly in this bacterium.
  
  
  OBJECTIVE
  Despite the considerable amount of research on the structure and assembly of other flagellar axial structures that has been conducted, the rod has been barely studied. An analysis of the biochemical characteristics of the flagellar rod components of the Fla1 system of R. sphaeroides is presented in this work. We also analyze the interactions of these proteins with each other and with their neighbors, and we propose a model for the order in which they are assembled.
authors.affiliation: Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico.
authors.forename: Manuel
authors.initials: M
authors.lastname: Osorio-Valeriano
authors.affiliation: Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico.
authors.forename: Javier
authors.initials: J
authors.lastname: de la Mora
authors.affiliation: Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico.
authors.forename: Laura
authors.initials: L
authors.lastname: Camarena
authors.affiliation: Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico gdreyfus@ifc.unam.mx.
authors.forename: Georges
authors.initials: G
authors.lastname: Dreyfus
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000235:genetics; D005407:Flagella / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology*; D008969:Molecular Sequence Data; D011487:Protein Conformation; D012242:Rhodobacter sphaeroides / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial