Monomerization of RepA dimers by heat shock proteins activates binding to DNA replication origin.
DnaK is a major heat shock protein of Escherichia coli and the homolog of hsp70 in eukaryotes. We demonstrate the mechanism by which DnaK and another heat shock protein, DnaJ, render the plasmid P1 initiator RepA 100-fold more active for binding to the P1 origin of replication. Activation is the conversion of RepA dimers into monomers in an ATP-dependent reaction and the monomer form binds with high affinity to oriP1 DNA. Reversible chemical denaturants also convert RepA dimers to monomers and simultaneously activate oriP1 DNA binding. Increasing protein concentration converts monomers to dimers and deactivates RepA. Based on our data and previous work, we present a model for heat shock protein action under normal and stress conditions.
Wickner
S
S
Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892.
Hoskins
J
J
McKenney
K
K
D000255:Adenosine Triphosphate / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D004265:DNA Helicases; D004261:DNA Replication; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism; D004926:Escherichia coli / Q000502:physiology*; D029968:Escherichia coli Proteins; D050956:HSP40 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D006358:Hot Temperature; D046911:Macromolecular Substances; D011485:Protein Binding; D011487:Protein Conformation; D011506:Proteins; D013329:Structure-Activity Relationship; D015534:Trans-Activators
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; C494635:DnaJ protein, E coli; D029968:Escherichia coli Proteins; D050956:HSP40 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D046911:Macromolecular Substances; D011506:Proteins; D015534:Trans-Activators; C045264:replication initiator protein; D000255:Adenosine Triphosphate; C063842:dnaK protein, E coli; D004265:DNA Helicases