129L

STRUCTURES OF RANDOMLY GENERATED MUTANTS OF T4 LYSOZYME SHOW THAT PROTEIN STABILITY CAN BE ENHANCED BY RELAXATION OF STRAIN AND BY IMPROVED HYDROGEN BONDING VIA BOUND SOLVENT

129L の概要

• エントリーDOI: 10.2210/pdb129l/pdb
• 分子名称: T4 LYSOZYME, CHLORIDE ION, BETA-MERCAPTOETHANOL, ... (4 entities in total)
• 機能のキーワード: hydrolase(o-glycosyl)
• 由来する生物種: Enterobacteria phage T4
• 細胞内の位置: Host cytoplasm : P00720
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 18885.56

構造登録者

Pjura, P.,Matthews, B.W. (登録日: 1993-05-28, 公開日: 1994-01-31, 最終更新日: 2024-02-07)

主引用文献

Pjura, P.,Matthews, B.W.
Structures of randomly generated mutants of T4 lysozyme show that protein stability can be enhanced by relaxation of strain and by improved hydrogen bonding via bound solvent.
Protein Sci., 2:2226-2232, 1993

PubMed Abstract: The structures of three mutants of bacteriophage T4 lysozyme selected using a screen designed to identify thermostable variants are described. Each of the mutants has a substitution involving threonine. Two of the variants, Thr 26-->Ser (T26S) and Thr 151-->Ser (T151S), have increased reversible melting temperatures with respect to the wild-type protein. The third, Ala 93-->Thr (A93T), has essentially the same stability as wild type. Thr 26 is in the wall of the active-site cleft. Its replacement with serine results in the rearrangement of nearby residues, most notably Tyr 18, suggesting that the increase in stability may result from the removal of strain. Thr 151 in the wild-type structure is far from the active site and appears to sterically prevent the access of solvent to a preformed binding site. In the mutant, the removal of the methyl group allows access to the solvent binding site and, in addition, the Ser 151 hydroxyl rotates to a new position so that it also contributes to solvent binding. Residue 93 is in a highly exposed site on the surface of the molecule, and presumably is equally solvent exposed in the unfolded protein. It is, therefore, not surprising that the substitution Ala 93-->Thr does not change stability. The mutant structures show how chemically similar mutations can have different effects on both the structure and stability of the protein, depending on the structural context. The results also illustrate the power of random mutagenesis in obtaining variants with a desired phenotype.(ABSTRACT TRUNCATED AT 250 WORDS)

PubMed: 8298466

実験手法

X-RAY DIFFRACTION (1.7 Å)