Hydrophobic effect on the stability and folding of a hyperthermophilic protein.


Ribonuclease HII from hyperthermophile Thermococcus kodakaraensis (Tk-RNase HII) is a kinetically robust monomeric protein. The conformational stability and folding kinetics of Tk-RNase HII were measured for nine mutant proteins in which a buried larger hydrophobic side chain is replaced by a smaller one (Leu/Ile to Ala). The mutant proteins were destabilized by 8.9 to 22.0 kJ mol(-1) as compared with the wild-type protein. The removal of each -CH(2)- group burial decreased the stability by 5.1 kJ mol(-1) on average in the mutant proteins of Tk-RNase HII examined. This is comparable with the value of 5.3 kJ mol(-1) obtained from experiments for proteins from organisms growing at moderate temperature. We conclude that the hydrophobic residues buried inside protein molecules contribute to the stabilization of hyperthermophilic proteins to a similar extent as proteins at normal temperature. In the folding experiments, the mutant proteins of Tk-RNase HII examined exhibited faster unfolding compared with the wild-type protein. These results indicate that the buried hydrophobic residues strongly contribute to the kinetic robustness of Tk-RNase HII. This is the first report that provides a practical cause of slow unfolding of hyperthermostable proteins. Study holds ProTherm entries: 23115, 23116, 23117, 23118, 23119, 23120, 23121, 23122, 23123, 23124, 23125, 23126, 23127, 23128, 23129, 23130, 23131, 23132, 23133, 23134 Extra Details: hydrophobic residue; stability; folding; hyperthermophilic protein; ribonuclease HII

Submission Details

ID: Yi4QEnNo3

Submitter: Connie Wang

Submission Date: April 24, 2018, 8:54 p.m.

Version: 1

Publication Details
Dong H;Mukaiyama A;Tadokoro T;Koga Y;Takano K;Kanaya S,J. Mol. Biol. (2008) Hydrophobic effect on the stability and folding of a hyperthermophilic protein. PMID:18353366
Additional Information

Structure view and single mutant data analysis

Study data

No weblogo for data of varying length.
Colors: D E R H K S T N Q A V I L M F Y W C G P

Data Distribution

Studies with similar sequences (approximate matches)

Correlation with other assays (exact sequence matches)

Relevant UniProtKB Entries

Percent Identity Matching Chains Protein Accession Entry Name
100.0 Ribonuclease HII O74035 RNH2_THEKO