MISC

基本情報

氏名 古賀 雄一
氏名(カナ) コガ ユウイチ
氏名(英語) Koga Yuuichi
所属 工学部 応用化学科
職名 教授
researchmap研究者コード 5000076449
researchmap機関 岡山理科大学

題名

Structural and thermodynamic analyses of Escherichia coli RNase HI variant with quintuple thermostabilizing mutations

単著・共著の別

 

著者

Mitsuru Haruki
Masaki Tanaka
Takehiko Motegi
Takashi Tadokoro
Yuichi Koga
Kazufumi Takano
Shigenori Kanaya

概要

A combination of five thermostabilizing mutations, Gly23 -> Ala, His62 -> Pro, Val74 -> Leu, Lys95 -> Gly, and Asp134 -> His, has been shown to additively enhance the thermostability of Escherichia coli RNase HI [Akasako A, Haruki M, Oobatake M & Kanaya S (1995) Biochemistry 34, 8115-8122]. In this study, we determined the crystal structure of the protein with these mutations (5H-RNase HI) to analyze the effects of the mutations on the structure in detail. The structures of the mutation sites were almost identical to those of the mutant proteins to which the mutations were individually introduced, except for G23A, for which the structure of the single mutant protein is not available. Moreover, only slight changes in the backbone conformation of the protein were observed, and the interactions of the side chains were almost conserved. These results indicate that these mutations almost independently affect the protein structure, and are consistent with the fact that the thermostabiling effects of the mutations are cumulative. We also determined the protein stability curve describing the temperature dependence of the free energy of unfolding of 5H-RNase HI to elucidate the thermostabilization mechanism. The maximal stability for 5H-RNase HI was as high as that for the cysteine-free variant of Thermus thermophilus RNase HI. In contrast, the heat capacity of unfolding for 5H-RNase H was similar to that for E. coli RNase HI, which is considerably higher than that for T. thermophilus RNase HI. These results suggest that 5H-RNase HI is stabilized, in part, by the thermostabilization mechanism adopted by T. thermophilus RNase HI.

発表雑誌等の名称

FEBS JOURNAL

出版者

BLACKWELL PUBLISHING

274

22

開始ページ

5815

終了ページ

5825

発行又は発表の年月

2007-11

査読の有無

無し

依頼の有無

無し

記述言語

英語

掲載種別

 

ISSN

 

ID:DOI

10.1111/j.1742-4658.2007-06104-x

ID:NAID(CiNiiのID)

 

ID:PMID

 

JGlobalID

 

arXiv ID

 

ORCIDのPut Code

 

DBLP ID