title: ClpX-mediated remodeling of mu transpososomes: selective unfolding of subunits destabilizes the entire complex.
abstract: E. coli ClpX, a member of the Clp/Hsp100 family of ATPases, remodels multicomponent complexes and facilitates ATP-dependent degradation. Here, we analyze the mechanism by which ClpX destabilizes the exceedingly stable Mu transpososome, a natural substrate for remodeling rather than degradation. We find that ClpX has the capacity to globally unfold transposase monomers, the building blocks of the transpososome. A biochemical probe for protein unfolding reveals that ClpX also unfolds MuA subunits during remodeling reactions, but that not all subunits have their structure extensively modified. In fact, direct recognition and unfolding of a single transposase subunit are sufficient for ClpX to destabilize the entire transpososome. Thus, the ability of ClpX to unfold proteins is sufficient to explain its role in both complex destabilization and ATP-dependent proteolysis.
authors.affiliation: Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
authors.forename: B M
authors.initials: BM
authors.lastname: Burton
authors.forename: T L
authors.initials: TL
authors.lastname: Williams
authors.forename: T A
authors.initials: TA
authors.lastname: Baker
mesh_terms: D000074183:ATPases Associated with Diverse Cellular Activities; D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism*; D018834:Chaperonin 60 / Q000378:metabolism; D049071:Endopeptidase Clp; D004795:Enzyme Stability; D029968:Escherichia coli Proteins; D015151:Immunoblotting; D046911:Macromolecular Substances; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism; D011489:Protein Denaturation; D017510:Protein Folding; D021122:Protein Subunits; D019895:Transposases / Q000235:genetics / Q000378:metabolism*
chemical_list: D018834:Chaperonin 60; D029968:Escherichia coli Proteins; D046911:Macromolecular Substances; D018832:Molecular Chaperones; D021122:Protein Subunits; C114697:mu transposase; D019895:Transposases; D049071:Endopeptidase Clp; D000251:Adenosine Triphosphatases; C088072:ClpX protein, E coli; D000074183:ATPases Associated with Diverse Cellular Activities