An amino acid residue in the middle of the fingers subdomain is involved in Neq DNA polymerase processivity: enhanced processivity of engineered Neq DNA polymerase and its PCR application

Protein Eng Des Sel. 2010 Nov;23(11):835-42. doi: 10.1093/protein/gzq059. Epub 2010 Sep 17.

Abstract

Neq DNA polymerase is the first archaeal family B DNA polymerase reported to lack uracil recognition function and successfully utilize deaminated bases. We have focused on two amino acid residues (Y515, A523) in the fingers subdomain of Neq DNA polymerase, which were predicted to be located in the middle of the fingers subdomain, based on amino acid sequence alignment of the Neq DNA polymerase with structurally determined archaeal DNA polymerases. Those two residues were replaced by site-directed mutagenesis, and the enzymatic properties of the mutants were analyzed. Here, we show that the A523 residue located in the middle of the fingers subdomain affects the processivity of Neq DNA polymerase. Mutational analysis has allowed us to enhance the protein function as well as understand the function of the residues. One mutant protein, Neq A523R DNA polymerase, exhibited a roughly 3-fold enhanced processivity and extension rate compared to wild type, enabling more efficient PCR. In the presence of uracil, Neq A523R DNA polymerase outperformed Taq DNA polymerase with enhanced specificity and sensitivity. These results suggest that Neq A523R DNA polymerase could be most effectively utilized in real-time PCR using uracil-DNA glycosylase without the risk of carry-over contamination.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • DNA Polymerase beta / chemistry
  • DNA Polymerase beta / genetics*
  • DNA Polymerase beta / isolation & purification
  • DNA Polymerase beta / metabolism*
  • DNA, Archaeal / metabolism*
  • Gene Expression
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed
  • Mutant Proteins / chemistry
  • Mutant Proteins / genetics
  • Mutant Proteins / isolation & purification
  • Mutant Proteins / metabolism
  • Nanoarchaeota / chemistry
  • Nanoarchaeota / enzymology*
  • Nanoarchaeota / metabolism
  • Polymerase Chain Reaction
  • Protein Engineering*
  • Sequence Alignment
  • Uracil / metabolism

Substances

  • DNA, Archaeal
  • Mutant Proteins
  • Uracil
  • DNA Polymerase beta