Structural and enzymatic studies of the T4 DNA replication system. I. Physical characterization of the polymerase accessory protein complex.
In this study, we have investigated the structural and physical properties of the bacteriophage T4 DNA polymerase accessory proteins. We find that T4 gene 44 and 62 proteins associate to form a tight, highly homogeneous complex, containing four gene 44 protein subunits and one gene 62 protein subunit. The molecular mass of the complex is 163,700 daltons. Sedimentation results suggest that the complex is quite asymmetric, with a prolate ellipsoid axial ratio of about 5:1. This protein complex is known to carry a DNA-dependent ATPase activity; we show by photoaffinity labeling that the ATP-binding sites reside in the gene 44 protein subunits of the complex. Equilibrium sedimentation and chemical cross-linking studies indicate that the T4 gene 45 protein self-associates to form a trimer in solution. This trimer species also appears to be quite asymmetric, showing an axial ratio for a prolate ellipsoid of about 6:1, assuming normal hydration.
Jarvis
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TC
Institute of Molecular Biology, University of Oregon, Eugene 97403.
Paul
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von Hippel
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PH
D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000378:metabolism; D000345:Affinity Labels / Q000378:metabolism; D001386:Azides / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D004261:DNA Replication; D004268:DNA-Binding Proteins / Q000302:isolation & purification / Q000378:metabolism*; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology*; D007700:Kinetics; D046911:Macromolecular Substances; D008970:Molecular Weight; D013604:T-Phages / Q000201:enzymology*; D014764:Viral Proteins / Q000302:isolation & purification / Q000378:metabolism*
D000345:Affinity Labels; D001386:Azides; D004268:DNA-Binding Proteins; D046911:Macromolecular Substances; D014764:Viral Proteins; C017040:8-azidoadenosine 5'-triphosphate; D000255:Adenosine Triphosphate; D004259:DNA-Directed DNA Polymerase