Nuclear Overhauser effect studies of the conformations and binding site environments of deoxynucleoside triphosphate substrates bound to DNA polymerase I and its large fragment. 1985

L J Ferrin, and A S Mildvan

The conformations and binding site environments of Mg2+TTP and Mg2+dATP bound to Escherichia coli DNA polymerase I and its large (Klenow) fragment have been investigated by proton NMR. The effect of the large fragment of Pol I on the NMR line widths of the protons of Mg2+TTP detected one binding site for this substrate with a dissociation constant of 300 +/- 100 microM and established simple competitive binding of deoxynucleoside triphosphates at this site in accord with previous equilibrium dialysis experiments with whole Pol I [Englund, P. T., Huberman, J.A., Jovin, T.M., & Kornberg, A. (1969) J. Biol. Chem. 244, 3038]. Primary negative nuclear Overhauser effects were used to calculate interproton distances on enzyme-bound Mg2+dATP and Mg2+TTP. These distances established that each substrate was bound with an anti-glycosidic torsional angle (chi) of 50 +/- 10 degrees for Mg2+dATP and 40 +/- 10 degrees for Mg2+TTP. The sugar pucker of both substrates was predominantly O1'-endo, with a C5'-C4'-C3'-O3' exocyclic torsional angle (delta) of 95 +/- 10 degrees for Mg2+dATP and 100 +/- 10 degrees for Mg2+TTP. The consistency of these conformations with those previously proposed, on the basis of distances from Mn2+ at the active site [Sloan, D. L., Loeb, L. A., Mildvan, A.S., & Feldman, R.J. (1975) J. Biol. Chem. 250, 8913], indicates a unique conformation for each bound nucleotide. The chi and delta values of the bound substrates are appropriate for nucleotide units of B DNA.(ABSTRACT TRUNCATED AT 250 WORDS)

UI MeSH Term Description Entries
D007700 Kinetics The rate dynamics in chemical or physical systems.
D008274 Magnesium A metallic element that has the atomic symbol Mg, atomic number 12, and atomic weight 24.31. It is important for the activity of many enzymes, especially those involved in OXIDATIVE PHOSPHORYLATION.
D009682 Magnetic Resonance Spectroscopy Spectroscopic method of measuring the magnetic moment of elementary particles such as atomic nuclei, protons or electrons. It is employed in clinical applications such as NMR Tomography (MAGNETIC RESONANCE IMAGING). In Vivo NMR Spectroscopy,MR Spectroscopy,Magnetic Resonance,NMR Spectroscopy,NMR Spectroscopy, In Vivo,Nuclear Magnetic Resonance,Spectroscopy, Magnetic Resonance,Spectroscopy, NMR,Spectroscopy, Nuclear Magnetic Resonance,Magnetic Resonance Spectroscopies,Magnetic Resonance, Nuclear,NMR Spectroscopies,Resonance Spectroscopy, Magnetic,Resonance, Magnetic,Resonance, Nuclear Magnetic,Spectroscopies, NMR,Spectroscopy, MR
D010446 Peptide Fragments Partial proteins formed by partial hydrolysis of complete proteins or generated through PROTEIN ENGINEERING techniques. Peptide Fragment,Fragment, Peptide,Fragments, Peptide
D011485 Protein Binding The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments. Plasma Protein Binding Capacity,Binding, Protein
D011487 Protein Conformation The characteristic 3-dimensional shape of a protein, including the secondary, supersecondary (motifs), tertiary (domains) and quaternary structure of the peptide chain. PROTEIN STRUCTURE, QUATERNARY describes the conformation assumed by multimeric proteins (aggregates of more than one polypeptide chain). Conformation, Protein,Conformations, Protein,Protein Conformations
D003854 Deoxyribonucleotides A purine or pyrimidine base bonded to a DEOXYRIBOSE containing a bond to a phosphate group. Deoxyribonucleotide
D004256 DNA Polymerase I A DNA-dependent DNA polymerase characterized in prokaryotes and may be present in higher organisms. It has both 3'-5' and 5'-3' exonuclease activity, but cannot use native double-stranded DNA as template-primer. It is not inhibited by sulfhydryl reagents and is active in both DNA synthesis and repair. DNA Polymerase alpha,DNA-Dependent DNA Polymerase I,Klenow Fragment,DNA Pol I,DNA Dependent DNA Polymerase I,Polymerase alpha, DNA
D004926 Escherichia coli A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc. Alkalescens-Dispar Group,Bacillus coli,Bacterium coli,Bacterium coli commune,Diffusely Adherent Escherichia coli,E coli,EAggEC,Enteroaggregative Escherichia coli,Enterococcus coli,Diffusely Adherent E. coli,Enteroaggregative E. coli,Enteroinvasive E. coli,Enteroinvasive Escherichia coli
D001665 Binding Sites The parts of a macromolecule that directly participate in its specific combination with another molecule. Combining Site,Binding Site,Combining Sites,Site, Binding,Site, Combining,Sites, Binding,Sites, Combining

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