1BOX

N39S MUTANT OF RNASE SA FROM STREPTOMYCES AUREOFACIENS

1BOX の概要

• エントリーDOI: 10.2210/pdb1box/pdb
• 分子名称: GUANYL-SPECIFIC RIBONUCLEASE SA (2 entities in total)
• 機能のキーワード: hydrolase, ribonuclease, mutant
• 由来する生物種: Streptomyces aureofaciens
• 細胞内の位置: Secreted: P05798
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 10555.47

構造登録者

Hebert, E.J.,Giletto, A.,Sevcik, J.,Urbanikova, L.,Wilson, K.S.,Dauter, Z.,Pace, C.N. (登録日: 1998-08-07, 公開日: 1999-12-29, 最終更新日: 2024-11-20)

主引用文献

Hebert, E.J.,Giletto, A.,Sevcik, J.,Urbanikova, L.,Wilson, K.S.,Dauter, Z.,Pace, C.N.
Contribution of a conserved asparagine to the conformational stability of ribonucleases Sa, Ba, and T1.
Biochemistry, 37:16192-16200, 1998

PubMed Abstract: The contribution of hydrogen bonding by peptide groups to the conformational stability of globular proteins was studied. One of the conserved residues in the microbial ribonuclease (RNase) family is an asparagine at position 39 in RNase Sa, 44 in RNase T1, and 58 in RNase Ba (barnase). The amide group of this asparagine is buried and forms two similar intramolecular hydrogen bonds with a neighboring peptide group to anchor a loop on the surface of all three proteins. Thus, it is a good model for the hydrogen bonding of peptide groups. When the conserved asparagine is replaced with alanine, the decrease in the stability of the mutant proteins is 2.2 (Sa), 1.8 (T1), and 2.7 (Ba) kcal/mol. When the conserved asparagine is replaced by aspartate, the stability of the mutant proteins decreases by 1.5 and 1.8 kcal/mol for RNases Sa and T1, respectively, but increases by 0.5 kcal/mol for RNase Ba. When the conserved asparagine was replaced by serine, the stability of the mutant proteins was decreased by 2.3 and 1.7 kcal/mol for RNases Sa and T1, respectively. The structure of the Asn 39 --> Ser mutant of RNase Sa was determined at 1.7 A resolution. There is a significant conformational change near the site of the mutation: (1) the side chain of Ser 39 is oriented differently than that of Asn 39 and forms hydrogen bonds with two conserved water molecules; (2) the peptide bond of Ser 42 changes conformation in the mutant so that the side chain forms three new intramolecular hydrogen bonds with the backbone to replace three hydrogen bonds to water molecules present in the wild-type structure; and (3) the loss of the anchoring hydrogen bonds makes the surface loop more flexible in the mutant than it is in wild-type RNase Sa. The results show that burial and hydrogen bonding of the conserved asparagine make a large contribution to microbial RNase stability and emphasize the importance of structural information in interpreting stability studies of mutant proteins.

PubMed: 9819211
DOI: 10.1021/bi9815243

実験手法

X-RAY DIFFRACTION (1.6 Å)