title: T5 DNA polymerase: structural--functional relationships to other DNA polymerases.
abstract: T5 DNA polymerase, a highly processive single-polypeptide enzyme, has been analyzed for its primary structural features. The amino acid sequence of T5 DNA polymerase has a high degree of homology with that of DNA polymerase I from Escherichia coli and retains many of the amino acid residues that have been implicated in the 3'----5' exonuclease and DNA polymerase activities of that enzyme. Alignment with sequences of polymerase I and T7 DNA polymerase was used to identify regions possibly involved in the high processivity of this enzyme. Further, amino acid sequence comparisons of T5 DNA polymerase with a large group of DNA polymerases previously shown to exhibit little similarity to polymerase I indicate certain sequence segments are shared among distantly related DNA polymerases. These shared regions have been implicated in the 3'----5' exonuclease function of polymerase I, which suggests that the proofreading domains of all these enzymes may be evolutionarily related.
authors.affiliation: Department of Microbiology and Immunology, University of Arizona Health Sciences Center, Tucson 85724.
authors.forename: M C
authors.initials: MC
authors.lastname: Leavitt
authors.forename: J
authors.initials: J
authors.lastname: Ito
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D004279:DNA, Viral / Q000235:genetics* / Q000302:isolation & purification; D004259:DNA-Directed DNA Polymerase / Q000235:genetics*; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D005796:Genes; D005814:Genes, Viral; D008969:Molecular Sequence Data; D015183:Restriction Mapping; D012689:Sequence Homology, Nucleic Acid; D013604:T-Phages / Q000201:enzymology* / Q000235:genetics
chemical_list: D004279:DNA, Viral; D004259:DNA-Directed DNA Polymerase