Skip Navigation


Journal of Biochemistry Advance Access originally published online on August 30, 2007
Journal of Biochemistry 2007 142(4):507-516; doi:10.1093/jb/mvm157
This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow All Versions of this Article:
142/4/507    most recent
mvm157v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrow Request Permissions
Google Scholar
Right arrow Articles by You, D.-J.
Right arrow Articles by Kanaya, S.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by You, D.-J.
Right arrow Articles by Kanaya, S.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?

© 2007 The Japanese Biochemical Society.

Protein Thermostabilization Requires a Fine-tuned Placement of Surface-charged Residues

Dong-Ju You1, Satoshi Fukuchi2, Ken Nishikawa2, Yuichi Koga1, Kazufumi Takano1,3,* and Shigenori Kanaya1

1Department of Material and Life Science, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan; 2Center for Information Biology and DNA Data Bank of Japan, National Institute of Genetics, 1111 Yata, Mishima, Shizuoka 411-8540, Japan; and 3CREST, JST, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan

*To whom correspondence should be addressed. Tel/Fax: +81-6-6879-4157, E-mail: ktakano{at}mls.eng.osaka-u.ac.jp

Received June 14, 2007; Accepted July 23, 2007


  Abstract

Using the information from the genome projects, recent comparative studies of thermostable proteins have revealed a certain trend of amino acid composition in which polar residues are scarce and charged residues are rich on the protein surface. To clarify experimentally the effect of the amino acid composition of surface residues on the thermostability of Escherichia coli Ribonuclease HI (RNase HI), we constructed six variants in which five to eleven polar residues were replaced by charged residues (5C, 7Ca, 7Cb, 9Ca, 9Cb and 11C). The thermal denaturation experiments indicated that all of the variant proteins are 3.2–10.1°C in Tm less stable than the wild proteins. The crystal structures of resultant protein variants 7Ca, 7Cb, 9Ca and 11C closely resemble that of E. coli RNase HI in their global fold, and several different hydrogen bonding and ion-pair interactions are formed by the mutations. Comparison of the crystal structures of these variant proteins with that of E. coli RNase HI reveals that thermal destabilization is apparently related to electrostatic repulsion of the charged residues with neighbours. This result suggests that charged residues of natural thermostable proteins are strictly posted on the surface with optimal interactions and without repulsive interactions.

Key Words: amino acid composition, genome information, RNase HI, surface-charge residue, thermostability

Abbreviations: CD, Circular dichroism; GdnHCl, guanidine hydrochloride; RNase H, Ribonuclease H


Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us    What's this?




Disclaimer: Please note that abstracts for content published before 1996 were created through digital scanning and may therefore not exactly replicate the text of the original print issues. All efforts have been made to ensure accuracy, but the Publisher will not be held responsible for any remaining inaccuracies. If you require any further clarification, please contact our Customer Services Department.