Primer-terminus stabilization at the psi 29 DNA polymerase active site. Mutational analysis of conserved motif TX2GR. 1994

J Méndez, and L Blanco, and J M Lázaro, and M Salas
Centro de Biología Molecular Severo Ochoa (C.S.I.C.-U.A.M.), Universidad Autónoma, Madrid, Spain.

The functional significance of the conserved motif TX2GR, included in one of the six main regions of amino acid sequence similarity identified in the C-terminal portion of both Escherichia coli DNA polymerase I-like and eukaryotic-type DNA polymerases (Blanco, L., Bernad, A., Blasco, M.A., and Salas, M. (1991) Gene (Amst.) 100, 27-38) has been studied by site-directed mutagenesis in the psi 29 DNA polymerase. A revised multiple alignment of this region, including 61 DNA polymerases belonging to these two superfamilies, is presented. In addition, based on amino acid sequence comparisons and by extrapolation to the crystal structure of T7 RNA polymerase, a similar motif (DX2GR) is predicted to be structurally and functionally equivalent in RNA polymerases, the other class of DNA-dependent polymerases. The severe defect in polymerization displayed by two of the psi 29 DNA polymerase mutants used in this study (T434N and R438I) is interpreted as the consequence of a decreased capacity to stabilize the binding of primer-template DNA structures in a polymerization-competent conformation. These mutants were also severely affected in the formation of terminal protein (TP)-dAMP initiation complex, a reaction in which psi 29 DNA polymerase is able to use the TP as primer.

UI MeSH Term Description Entries
D008969 Molecular Sequence Data Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories. Sequence Data, Molecular,Molecular Sequencing Data,Data, Molecular Sequence,Data, Molecular Sequencing,Sequencing Data, Molecular
D004247 DNA A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine). DNA, Double-Stranded,Deoxyribonucleic Acid,ds-DNA,DNA, Double Stranded,Double-Stranded DNA,ds DNA
D004252 DNA Mutational Analysis Biochemical identification of mutational changes in a nucleotide sequence. Mutational Analysis, DNA,Analysis, DNA Mutational,Analyses, DNA Mutational,DNA Mutational Analyses,Mutational Analyses, DNA
D004259 DNA-Directed DNA Polymerase DNA-dependent DNA polymerases found in bacteria, animal and plant cells. During the replication process, these enzymes catalyze the addition of deoxyribonucleotide residues to the end of a DNA strand in the presence of DNA as template-primer. They also possess exonuclease activity and therefore function in DNA repair. DNA Polymerase,DNA Polymerases,DNA-Dependent DNA Polymerases,DNA Polymerase N3,DNA Dependent DNA Polymerases,DNA Directed DNA Polymerase,DNA Polymerase, DNA-Directed,DNA Polymerases, DNA-Dependent,Polymerase N3, DNA,Polymerase, DNA,Polymerase, DNA-Directed DNA,Polymerases, DNA,Polymerases, DNA-Dependent DNA
D004261 DNA Replication The process by which a DNA molecule is duplicated. Autonomous Replication,Replication, Autonomous,Autonomous Replications,DNA Replications,Replication, DNA,Replications, Autonomous,Replications, DNA
D005090 Exodeoxyribonucleases A family of enzymes that catalyze the exonucleolytic cleavage of DNA. It includes members of the class EC 3.1.11 that produce 5'-phosphomonoesters as cleavage products. DNA Exonucleases,Exonucleases, DNA
D000595 Amino Acid Sequence The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION. Protein Structure, Primary,Amino Acid Sequences,Sequence, Amino Acid,Sequences, Amino Acid,Primary Protein Structure,Primary Protein Structures,Protein Structures, Primary,Structure, Primary Protein,Structures, Primary Protein
D001483 Base Sequence The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence. DNA Sequence,Nucleotide Sequence,RNA Sequence,DNA Sequences,Base Sequences,Nucleotide Sequences,RNA Sequences,Sequence, Base,Sequence, DNA,Sequence, Nucleotide,Sequence, RNA,Sequences, Base,Sequences, DNA,Sequences, Nucleotide,Sequences, RNA
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
D013698 Templates, Genetic Macromolecular molds for the synthesis of complementary macromolecules, as in DNA REPLICATION; GENETIC TRANSCRIPTION of DNA to RNA, and GENETIC TRANSLATION of RNA into POLYPEPTIDES. Genetic Template,Genetic Templates,Template, Genetic

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