title: Disassembly of the Mu transposase tetramer by the ClpX chaperone.
abstract: Mu transposition is promoted by an extremely stable complex containing a tetramer of the transposase (MuA) bound to the recombining DNA. Here we purify the Escherichia coli ClpX protein, a member of a family of multimeric ATPases present in prokaryotes and eukaryotes (the Clp family), on the basis of its ability to remove the transposase from the DNA after recombination. Previously, ClpX has been shown to function with the ClpP peptidase in protein turnover. However, neither ClpP nor any other protease is required for disassembly of the transposase. The released MuA is not modified extensively, degraded, or irreversibly denatured, and is able to perform another round of recombination in vitro. We conclude that ClpX catalyzes the ATP-dependent release of MuA by promoting a transient conformational change in the protein and, therefore, can be considered a molecular chaperone. ClpX is important at the transition between the recombination and DNA replication steps of transposition in vitro; this function probably corresponds to the essential contribution of ClpX for Mu growth. Deletion analysis reveals that the sequence at the carboxyl terminus of MuA is important for disassembly by ClpX and can target MuA for degradation by ClpXP in vitro. These data contribute to the emerging picture that members of the Clp family are chaperones specifically suited for disaggregating proteins and are able to function with or without a collaborating protease.
authors.affiliation: Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge 02139, USA.
authors.forename: I
authors.initials: I
authors.lastname: Levchenko
authors.forename: L
authors.initials: L
authors.lastname: Luo
authors.forename: T A
authors.initials: TA
authors.lastname: Baker
mesh_terms: D000074183:ATPases Associated with Diverse Cellular Activities; D000251:Adenosine Triphosphatases / Q000302:isolation & purification / Q000378:metabolism* / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D010583:Bacteriophage mu / Q000201:enzymology* / Q000235:genetics; D001483:Base Sequence; D015153:Blotting, Western; D002499:Centrifugation, Density Gradient; D017931:DNA Primers; D004261:DNA Replication; D004279:DNA, Viral / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004587:Electrophoresis, Agar Gel; D004591:Electrophoresis, Polyacrylamide Gel; D049071:Endopeptidase Clp; D004926:Escherichia coli / Q000737:chemistry*; D029968:Escherichia coli Proteins; D018832:Molecular Chaperones / Q000302:isolation & purification / Q000378:metabolism*; D008969:Molecular Sequence Data; D009713:Nucleotidyltransferases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012697:Serine Endopeptidases / Q000378:metabolism; D019895:Transposases
chemical_list: D017931:DNA Primers; D004279:DNA, Viral; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D018832:Molecular Chaperones; D000255:Adenosine Triphosphate; D009713:Nucleotidyltransferases; D019895:Transposases; D012697:Serine Endopeptidases; C483573:ClpXP protease, E coli; D049071:Endopeptidase Clp; D000251:Adenosine Triphosphatases; C088072:ClpX protein, E coli; D000074183:ATPases Associated with Diverse Cellular Activities