Favorable contribution of the C-terminal residue K97 to the stability of a hyperthermophilic archaeal [P62A]Ssh10b.
The role of residue K97 at the C-terminal end of archaeal [P62A]Ssh10b in the hyperthermostability of the protein is investigated using three K97-mutant variants: K97E-, K97A-, and DeltaK97-mutant [P62A]Ssh10b. The thermal- and GdmHCl-induced denaturation of the three mutant variants has been monitored by circular dichroism. The results reveal that the K97E mutation leads to a stronger destabilization effect than the K97A mutation by disturbing the electrostatic interaction of the salt-bridge D63-K97 and drawing an unfavorable charge-charge repulsive interaction into the structure. However, DeltaK97-[P62A]Ssh10b shows much lower stability than K97E- and K97A-mutant [P62A]Ssh10b. Analysis suggests that residue K97 at the C-terminal end makes the favorable contributions to the stability of hyperthermophilic [P62A]Ssh10b not only by the favorable electrostatic interactions with residues in close vicinity but also through maintaining the side chain packing of the surrounding residues in the C-terminal area of the protein.
Fang
Xianyang
X
National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing, China.
Feng
Yingang
Y
Wang
Jinfeng
J
D000595:Amino Acid Sequence; D019843:Archaeal Proteins / Q000737:chemistry* / Q000235:genetics; D002942:Circular Dichroism; D007700:Kinetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D011487:Protein Conformation; D017510:Protein Folding; D055672:Static Electricity; D013816:Thermodynamics
D019843:Archaeal Proteins