2QXT

Crystal Structure Analysis of the Bacillus subtilis lipase crystallized at pH 4.5

2QXT の概要

• エントリーDOI: 10.2210/pdb2qxt/pdb
• 関連するPDBエントリー: 2QXU
• 分子名称: Lipase (2 entities in total)
• 機能のキーワード: alpha/beta hydrolase fold, lipid degradation, secreted, hydrolase
• 由来する生物種: Bacillus subtilis
• 細胞内の位置: Secreted: P37957
• タンパク質・核酸の鎖数: 2
• 化学式量合計: 38365.29

構造登録者

Rajakumara, E.,Sankaranarayanan, R. (登録日: 2007-08-13, 公開日: 2007-12-18, 最終更新日: 2023-10-25)

主引用文献

Rajakumara, E.,Acharya, P.,Ahmad, S.,Sankaranaryanan, R.,Rao, N.M.
Structural basis for the remarkable stability of Bacillus subtilis lipase (Lip A) at low pH
Biochim.Biophys.Acta, 1784:302-311, 2008

PubMed Abstract: Understanding the structural basis of altered properties of proteins due to changes in temperature or pH provides useful insights in designing proteins with improved stability. Here we report the basis for the pH-dependent thermostability of the Bacillus subtilis lipase (Lip A) using spectroscopic and X-ray crystallographic studies. At pH values above 7, lipase denatures and aggregates when heated at temperatures above 45 degrees C. However, at pH below 6 lipase denatures upon heating but the activity and its native structure is completely recovered upon cooling. In order to obtain the structural basis of this unusual stability of lipase, we determined high-resolution crystal structures of the lipase in two different crystal forms at pH 4.5 and 5. These structures show linear oligomerization of lipase using only two types of dimeric associations and these inter-molecular interactions are completely absent in several crystal forms of wild-type and mutant proteins obtained at basic pH. In accordance with the crystallographic studies, spectroscopic investigations reveal an invariant secondary structure in the pH range of 4-10. Quaternary organization of lipase at low pH resulted in changes in the tryptophan environment and binding of 1-anilino-8-naphthalene sulfate (ANS) at low pH. Low pH stability of the lipase is not observed in the presence of sodium chloride (>0.2 M) indicating the importance of ionic interactions at low pH. Inter- and intra-molecular ionic interactions that occur at pH below 6.0 are proposed to trap the molecule in a conformation that allows its complete refolding upon cooling.

PubMed: 18053819
DOI: 10.1016/j.bbapap.2007.10.012

実験手法

X-RAY DIFFRACTION (2 Å)