title: Mechanism of homotropic control to coordinate hydrolysis in a hexameric AAA+ ring ATPase.
abstract: AAA(+) proteins are ubiquitous mechanochemical ATPases that use energy from ATP hydrolysis to remodel their versatile substrates. The AAA(+) characteristic hexameric ring assemblies raise important questions about if and how six often identical subunits coordinate hydrolysis and associated motions. The PspF AAA(+) domain, PspF(1-275), remodels the bacterial sigma(54)-RNA polymerase to activate transcription. Analysis of ATP substrate inhibition kinetics on ATP hydrolysis in hexameric PspF(1-275) indicates negative homotropic effects between subunits. Functional determinants required for allosteric control identify: (i) an important link between the ATP bound ribose moiety and the SensorII motif that would allow nucleotide-dependent *-helical */beta subdomain dynamics; and (ii) establishes a novel regulatory role for the SensorII helix in PspF, which may apply to other AAA(+) proteins. Consistent with functional data, homotropic control appears to depend on nucleotide state-dependent subdomain angles imposing dynamic symmetry constraints in the AAA(+) ring. Homotropic coordination is functionally important to remodel the sigma(54) promoter. We propose a structural symmetry-based model for homotropic control in the AAA(+) characteristic ring architecture.
authors.affiliation: Division of Biology, Imperial College London, London SW7 2AZ, UK. j.schumacher@imperial.ac.uk
authors.forename: Jörg
authors.initials: J
authors.lastname: Schumacher
authors.forename: Nicolas
authors.initials: N
authors.lastname: Joly
authors.forename: Inaki Leoz
authors.initials: IL
authors.lastname: Claeys-Bouuaert
authors.forename: Shaniza Abdul
authors.initials: SA
authors.lastname: Aziz
authors.forename: Mathieu
authors.initials: M
authors.lastname: Rappas
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Zhang
authors.forename: Martin
authors.initials: M
authors.lastname: Buck
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism; D000251:Adenosine Triphosphatases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism; D000494:Allosteric Regulation; D002850:Chromatography, Gel; D004926:Escherichia coli / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D006868:Hydrolysis; D007700:Kinetics; D008958:Models, Molecular; D009154:Mutation / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D020836:Protein Structure, Quaternary; D021122:Protein Subunits / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D051877:RNA Polymerase Sigma 54 / Q000235:genetics / Q000378:metabolism; D015534:Trans-Activators / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism
chemical_list: D029968:Escherichia coli Proteins; D021122:Protein Subunits; C098954:PspF protein, E coli; D015534:Trans-Activators; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D051877:RNA Polymerase Sigma 54; D000251:Adenosine Triphosphatases