title: Dissecting the role of a conserved motif (the second region of homology) in the AAA family of ATPases. Site-directed mutagenesis of the ATP-dependent protease FtsH.
abstract: Escherichia coli FtsH is an ATP-dependent protease that belongs to the AAA protein family. The second region of homology (SRH) is a highly conserved motif among AAA family members and distinguishes these proteins in part from the wider family of Walker-type ATPases. Despite its conservation across the AAA family of proteins, very little is known concerning the function of the SRH. To address this question, we introduced point mutations systematically into the SRH of FtsH and studied the activities of the mutant proteins. Highly conserved amino acid residues within the SRH were found to be critical for the function of FtsH, with mutations at these positions leading to decreased or abolished ATPase activity. The effects of the mutations on the protease activity of FtsH correlated strikingly with their effects on the ATPase activity. The ATPase-deficient SRH mutants underwent an ATP-induced conformational change similar to wild type FtsH, suggesting an important role for the SRH in ATP hydrolysis but not ATP binding. Analysis of the data in the light of the crystal structure of the hexamerization domain of N-ethylmaleimide-sensitive fusion protein suggests a plausible mechanism of ATP hydrolysis by the AAA ATPases, which invokes an intermolecular catalytic role for the SRH.
authors.affiliation: Department of Molecular Cell Biology, Institute of Molecular Embryology, Kumamoto University School of Medicine, Kumamoto 862-0976, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Karata
authors.forename: T
authors.initials: T
authors.lastname: Inagawa
authors.forename: A J
authors.initials: AJ
authors.lastname: Wilkinson
authors.forename: T
authors.initials: T
authors.lastname: Tatsuta
authors.forename: T
authors.initials: T
authors.lastname: Ogura
mesh_terms: D049069:ATP-Dependent Proteases; D000251:Adenosine Triphosphatases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000737:chemistry; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D017124:Conserved Sequence; D004926:Escherichia coli / Q000201:enzymology; D029968:Escherichia coli Proteins; D008565:Membrane Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011487:Protein Conformation; D017386:Sequence Homology, Amino Acid
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D000255:Adenosine Triphosphate; D049069:ATP-Dependent Proteases; C513383:FtsH protein, E coli; D000251:Adenosine Triphosphatases