title: Interaction of FliI, a component of the flagellar export apparatus, with flagellin and hook protein.
abstract: FliI is a key component of the flagellar export apparatus in Salmonella typhimurium. It catalyzes the hydrolysis of ATP which is necessary for flagellar assembly. Affinity blotting experiments showed that purified flagellin and hook protein, two flagellar axial proteins, interact specifically with FliI. The interaction of either of the two proteins with FliI, increases the intrinsic ATPase activity. The presence of either flagellin or hook protein stimulates ATPase activity in a specific and reversible manner. A Vmax of 0.12 nmol Pi min-1 microgram-1 and a Km for MgATP of 0.35 mM was determined for the unstimulated FliI; the presence of flagellin increased the Vmax to 0.35 nmol Pi min-1 microgram-1 and the Km for MgATP to 1.1 mM. The stimulation induced by the axial proteins was fully reversible suggesting a direct link between the catalytic activity of FliI and the export process.
authors.affiliation: Departamento de Genética Molecular, Instituto de Fisiología Celular, UNAM, Apdo. Postal 70-600, 04510, México D.F., Mexico.
authors.forename: E
authors.initials: E
authors.lastname: Silva-Herzog
authors.forename: G
authors.initials: G
authors.lastname: Dreyfus
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000737:chemistry / Q000378:metabolism; D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D004789:Enzyme Activation; D004926:Escherichia coli / Q000378:metabolism; D005407:Flagella / Q000737:chemistry*; D005408:Flagellin / Q000737:chemistry / Q000378:metabolism*; D006868:Hydrolysis; D007700:Kinetics; D010957:Plasmids; D014176:Protein Biosynthesis; D011506:Proteins / Q000737:chemistry / Q000378:metabolism*; D006180:Proton-Translocating ATPases; D012486:Salmonella typhimurium; D012697:Serine Endopeptidases
chemical_list: D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D011506:Proteins; D005408:Flagellin; C069251:fliI protein, bacteria; D000255:Adenosine Triphosphate; D012697:Serine Endopeptidases; D000251:Adenosine Triphosphatases; D006180:Proton-Translocating ATPases