ClpX and MuB interact with overlapping regions of Mu transposase: implications for control of the transposition pathway.
Transposition of phage Mu is catalyzed by an extremely stable transposase-DNA complex. Once recombination is complete, the Escherichia coli ClpX protein, a member of the Clp/Hsp100 chaperone family, initiates disassembly of the complex for phage DNA replication to commence. To understand how the transition between recombination and replication is controlled, we investigated how transposase-DNA complexes are recognized by ClpX. We find that a 10-amino-acid peptide from the carboxy-terminal domain of transposase is required for its recognition by ClpX. This short, positively charged peptide is also sufficient to convert a heterologous protein into a ClpX substrate. The region of transposase that interacts with the transposition activator, MuB protein, is also defined further and found to overlap with that recognized by ClpX. As a consequence, MuB inhibits disassembly of several transposase-DNA complexes that are intermediates in recombination. This ability of MuB to block access to transposase suggests a mechanism for restricting ClpX-mediated remodeling to the proper stage during replicative transposition. We propose that overlap of sequences involved in subunit interactions and those that target a protein for remodeling or destruction may be a useful design for proteins that function in pathways where remodeling or degradation must be regulated.
Levchenko
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Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of Technology, Cambridge 02139, USA.
Yamauchi
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Baker
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D000074183:ATPases Associated with Diverse Cellular Activities; D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000595:Amino Acid Sequence; D010583:Bacteriophage mu / Q000235:genetics / Q000502:physiology*; D001665:Binding Sites; D004254:DNA Nucleotidyltransferases / Q000737:chemistry* / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D049071:Endopeptidase Clp; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics / Q000821:virology*; D029968:Escherichia coli Proteins; D007700:Kinetics; D008961:Models, Structural; D018832:Molecular Chaperones; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D016133:Polymerase Chain Reaction; D011994:Recombinant Proteins / Q000378:metabolism; D011995:Recombination, Genetic; D019895:Transposases; D014764:Viral Proteins / Q000378:metabolism*
D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D018832:Molecular Chaperones; C069215:MuB protein, Enterobacteria phage Mu; D011994:Recombinant Proteins; D014764:Viral Proteins; D004254:DNA Nucleotidyltransferases; D019895:Transposases; D049071:Endopeptidase Clp; D000251:Adenosine Triphosphatases; C088072:ClpX protein, E coli; D000074183:ATPases Associated with Diverse Cellular Activities