Multiple Conformations of the Loop Region Confers Heat-Resistance on SsArd1, a Thermophilic NatA

Chembiochem. 2016 Feb 2;17(3):214-7. doi: 10.1002/cbic.201500568. Epub 2015 Dec 10.


Structural comparison indicates that the loop region between β3 and β4 of SsArd1 is extended relative to the corresponding region in mesophilic Nats, and forms a plastic hydrogen-bond network mainly at two serine residues. Strikingly, two single-point mutants showed ∼3 °C decrease in melting temperature, and two other variants showed ∼7 °C decrease; this correlated with significantly reduced enzymatic activity. To our knowledge, this is the first discovery of a loop region capable of remarkably improving protein thermostability. This provides a novel route to engineer heat-resistant proteins.

Keywords: acetyltransferase; biophysics; crystallization; enzymes; thermostability.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Archaeal Proteins / chemistry
  • Archaeal Proteins / genetics
  • Archaeal Proteins / metabolism*
  • Biocatalysis
  • Circular Dichroism
  • Hydrogen Bonding
  • Mutagenesis, Site-Directed
  • N-Terminal Acetyltransferase A / chemistry
  • N-Terminal Acetyltransferase A / genetics
  • N-Terminal Acetyltransferase A / metabolism*
  • Protein Structure, Secondary
  • Protein Structure, Tertiary
  • Sulfolobus solfataricus / metabolism
  • Thermodynamics
  • Transition Temperature


  • Archaeal Proteins
  • N-Terminal Acetyltransferase A