1KAA

STRESS AND STRAIN IN STAPHYLOCOCCAL NUCLEASE

1KAA の概要

• エントリーDOI: 10.2210/pdb1kaa/pdb
• 分子名称: STAPHYLOCOCCAL NUCLEASE (2 entities in total)
• 機能のキーワード: hydrolase(phosphoric diester)
• 由来する生物種: Staphylococcus aureus
• 細胞内の位置: Nuclease A: Secreted. Nuclease B: Membrane: P00644
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 15478.95

構造登録者

Hodel, A.,Fox, R.O. (登録日: 1992-12-18, 公開日: 1994-01-31, 最終更新日: 2024-02-07)

主引用文献

Hodel, A.,Kautz, R.A.,Jacobs, M.D.,Fox, R.O.
Stress and strain in staphylococcal nuclease.
Protein Sci., 2:838-850, 1993

PubMed Abstract: Protein molecules generally adopt a tertiary structure in which all backbone and side chain conformations are arranged in local energy minima; however, in several well-refined protein structures examples of locally strained geometries, such as cis peptide bonds, have been observed. Staphylococcal nuclease A contains a single cis peptide bond between residues Lys 116 and Pro 117 within a type VIa beta-turn. Alternative native folded forms of nuclease A have been detected by NMR spectroscopy and attributed to a mixture of cis and trans isomers at the Lys 116-Pro 117 peptide bond. Analyses of nuclease variants K116G and K116A by NMR spectroscopy and X-ray crystallography are reported herein. The structure of K116A is indistinguishable from that of nuclease A, including a cis 116-117 peptide bond (92% populated in solution). The overall fold of K116G is also indistinguishable from nuclease A except in the region of the substitution (residues 112-117), which contains a predominantly trans Gly 116-Pro 117 peptide bond (80% populated in solution). Both Lys and Ala would be prohibited from adopting the backbone conformation of Gly 116 due to steric clashes between the beta-carbon and the surrounding residues. One explanation for these results is that the position of the ends of the residue 112-117 loop only allow trans conformations where the local backbone interactions associated with the phi and psi torsion angles are strained. When the 116-117 peptide bond is cis, less strained backbone conformations are available. Thus the relaxation of the backbone strain intrinsic to the trans conformation compensates for the energetically unfavorable cis X-Pro peptide bond. With the removal of the side chain from residue 116 (K116G), the backbone strain of the trans conformation is reduced to the point that the conformation associated with the cis peptide bond is no longer favorable.

PubMed: 8495201

実験手法

X-RAY DIFFRACTION (1.9 Å)