title: Unique contacts direct high-priority recognition of the tetrameric Mu transposase-DNA complex by the AAA+ unfoldase ClpX.
abstract: Clp/Hsp100 ATPases remodel and disassemble multiprotein complexes, yet little is known about how they preferentially recognize these complexes rather than their constituent subunits. We explore how substrate multimerization modulates recognition by the ClpX unfoldase using a natural substrate, MuA transposase. MuA is initially monomeric but forms a stable tetramer when bound to transposon DNA. Destabilizing this tetramer by ClpX promotes an essential transition in the phage Mu recombination pathway. We show that ClpX interacts more tightly with tetrameric than with monomeric MuA. Residues exposed only in the MuA tetramer are important for enhanced recognition--which requires the N domain of ClpX--as well as for a high maximal disassembly rate. We conclude that an extended set of potential enzyme contacts are exposed upon assembly of the tetramer and function as internal guides to recruit ClpX, thereby ensuring that the tetrameric complex is a high-priority substrate.
authors.affiliation: Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
authors.forename: Aliaa H
authors.initials: AH
authors.lastname: Abdelhakim
authors.forename: Elizabeth C
authors.initials: EC
authors.lastname: Oakes
authors.forename: Robert T
authors.initials: RT
authors.lastname: Sauer
authors.forename: Tania A
authors.initials: TA
authors.lastname: Baker
mesh_terms: D000074183:ATPases Associated with Diverse Cellular Activities; D000251:Adenosine Triphosphatases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001665:Binding Sites; D004247:DNA / Q000737:chemistry / Q000378:metabolism*; D049071:Endopeptidase Clp / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D046911:Macromolecular Substances / Q000737:chemistry / Q000378:metabolism; D008958:Models, Molecular; D018832:Molecular Chaperones / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D017354:Point Mutation; D011485:Protein Binding; D020836:Protein Structure, Quaternary; D019895:Transposases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: D029968:Escherichia coli Proteins; D046911:Macromolecular Substances; D018832:Molecular Chaperones; D004247:DNA; C114697:mu transposase; D019895:Transposases; D049071:Endopeptidase Clp; D000251:Adenosine Triphosphatases; C088072:ClpX protein, E coli; D000074183:ATPases Associated with Diverse Cellular Activities