title: trans-Acting arginine residues in the AAA+ chaperone ClpB allosterically regulate the activity through inter- and intradomain communication.
abstract: The molecular chaperone ClpB/Hsp104, a member of the AAA+ superfamily (ATPases associated with various cellular activities), rescues proteins from the aggregated state in collaboration with the DnaK/Hsp70 chaperone system. ClpB/Hsp104 forms a hexameric, ring-shaped complex that functions as a tightly regulated, ATP-powered molecular disaggregation machine. Highly conserved and essential arginine residues, often called arginine fingers, are located at the subunit interfaces of the complex, which also harbor the catalytic sites. Several AAA+ proteins, including ClpB/Hsp104, possess a pair of such trans-acting arginines in the N-terminal nucleotide binding domain (NBD1), both of which were shown to be crucial for oligomerization and ATPase activity. Here, we present a mechanistic study elucidating the role of this conserved arginine pair. First, we found that the arginines couple nucleotide binding to oligomerization of NBD1, which is essential for the activity. Next, we designed a set of covalently linked, dimeric ClpB NBD1 variants, carrying single subunits deficient in either ATP binding or hydrolysis, to study allosteric regulation and intersubunit communication. Using this well defined environment of site-specifically modified, cross-linked AAA+ domains, we found that the conserved arginine pair mediates the cooperativity of ATP binding and hydrolysis in an allosteric fashion.
authors.affiliation: From the Department of Biomolecular Mechanisms, Max Planck Institute for Medical Research, 69120 Heidelberg, Germany.
authors.forename: Cathleen
authors.initials: C
authors.lastname: Zeymer
authors.affiliation: From the Department of Biomolecular Mechanisms, Max Planck Institute for Medical Research, 69120 Heidelberg, Germany.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Fischer
authors.affiliation: From the Department of Biomolecular Mechanisms, Max Planck Institute for Medical Research, 69120 Heidelberg, Germany jochen.reinstein@mpimf-heidelberg.mpg.de.
authors.forename: Jochen
authors.initials: J
authors.lastname: Reinstein
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000737:chemistry / Q000378:metabolism; D000494:Allosteric Regulation; D001120:Arginine / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites / Q000235:genetics; D006360:Heat-Shock Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006868:Hydrolysis; D007700:Kinetics; D008958:Models, Molecular; D018832:Molecular Chaperones / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D011485:Protein Binding; D055503:Protein Multimerization; D017434:Protein Structure, Tertiary; D016963:Thermus thermophilus / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D006360:Heat-Shock Proteins; D018832:Molecular Chaperones; D000255:Adenosine Triphosphate; D001120:Arginine; D000251:Adenosine Triphosphatases
keywords: ATPase; ATPases Associated with Diverse Cellular Activities (AAA); Allosteric Regulation; Arginine Finger; ClpB; Hsp104; Molecular Chaperone; Nucleotide Binding; Oligomerization