Skip Navigation

This Article
Right arrow Full Text (PDF)
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 Search for citing articles in:
ISI Web of Science (49)
Right arrowRequest Permissions
Google Scholar
Right arrow Articles by Ishikawa, K.
Right arrow Articles by Nakamura, H.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Ishikawa, K.
Right arrow Articles by Nakamura, H.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?

Protein Engineering vol. 6 no. 1 pp. 85-91, 1993
© 1993 Oxford University Press

RESEARCH-ARTICLE

Structural study of mutants of Escherichia coli ribonuclease HI with enhanced thermostability

Kohki Ishikawa, Shigenobu Kimura1, Shigenori Kanaya, Kosuke Morikawa and Haruki Nakamura2

Protein Engineering Research Institute 6-2-3, Furuedai, Suita, Osaka 565, Japan 1Present address: Basic Research Laboratories, Toray Industries, Inc. 1,111, Tebiro, Kamakura, Kanagawa 248, Japan

2To whom correspondence should be addressed

Systematic replacement of the amino acid residues in Escherichia coli ribonuclease HI with those in the thermophilic counterpart has revealed that two mutations, His62–Pro (H62P) and Lys95->Gly (K95G), increased the thermostability of the protein. These single-site mutant proteins, together with the mutant proteins His62->Ala (H62A), Lys95->Asn (K95N) and Lys95->Ala (K95A), were crystallized and their structures were determined at 1.8 Å resolution. The crystal structures of these mutant proteins reveal that only the local structure around each mutation site is essential for the increase in thermostability. For each mutant protein, the stabilization mechanism is considered to be as follows: (i) H62P is stabilized because of a decrease in the entropy of the unfolded state, without a change in the native backbone structure; (ii) K95G is stabilized since the strain caused by the left-handed backbone structure in the typical 3:5 type loop is eliminated; and (iii) K95N is slightly stabilized by a hydrogen bond formed between the side-chain N{delta}-atom of the mutated aspargine residue and the main-chain carbonyl oxygen within the same residue.

Keywords: ribonuclease H/site-directed mutagenesis/thermo-stability/X-ray crystallography


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


This article has been cited by other articles:


Home page
 J. Biol. Chem.Home page
A. Akasako, M. Haruki, M. Oobatake, and S. Kanaya
Conformational Stabilities of Escherichia coli RNase HI Variants with a Series of Amino Acid Substitutions at a Cavity within the Hydrophobic Core
J. Biol. Chem., July 25, 1997; 272(30): 18686 - 18693.
[Abstract] [Full Text] [PDF]


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.