Prokaryotic DNA polymerase I: evolution, structure, and "base flipping" mechanism for nucleotide selection

J Mol Biol. 2001 May 18;308(5):823-37. doi: 10.1006/jmbi.2001.4619.

Abstract

Accurate transmission of DNA material from one generation to the next is crucial for prolonged cell survival. Following the discovery of DNA polymerse I in Escherichia coli, the DNA polymerase I class of enzymes has served as the prototype for studies on structural and biochemical mechanisms of DNA replication. Recently, a series of genomic, mutagenesis and structural investigations have provided key insights into how Pol I class of enzymes function and evolve. X-ray crystal structures of at least three Pol I class of enzymes have been solved in the presence of DNA and dNTP, thus allowing a detailed description of a productive replication complex. Rapid-quench stop-flow studies have helped define individual steps during nucleotide incorporation and conformational changes that are rate limiting during catalysis. Studies in our laboratory have generated large libraries of active mutant enzymes (8000) containing a variety of substitutions within the active site, some of which exhibit altered biochemical properties. Extensive genomic information of Pol I has recently become available, as over 50 polA genes from different prokaryotic species have been sequenced. In light of these advancements, we review here the structure-function relationships of Pol I, and we highlight those interactions that are responsible for the high fidelity of DNA synthesis. We present a mechanism for "flipping" of the complementary template base to enhance interactions with the incoming nucleotide substrate during DNA synthesis.

Publication types

  • Review

MeSH terms

  • Amino Acid Sequence
  • Bacterial Proteins / chemistry
  • Bacterial Proteins / metabolism
  • Base Pairing
  • Binding Sites
  • DNA Polymerase I / chemistry*
  • DNA Polymerase I / metabolism*
  • DNA Replication
  • Evolution, Molecular*
  • Molecular Sequence Data
  • Nucleotides / metabolism*
  • Protein Conformation
  • Substrate Specificity

Substances

  • Bacterial Proteins
  • Nucleotides
  • DNA Polymerase I