2Q4G

Ensemble refinement of the protein crystal structure of human ribonuclease inhibitor complexed with ribonuclease I

2Q4G の概要

• エントリーDOI: 10.2210/pdb2q4g/pdb
• 分子名称: Ribonuclease pancreatic, Ribonuclease inhibitor, CITRIC ACID, ... (4 entities in total)
• 機能のキーワード: ensemble refinement, refinement methodology development, ribonuclease-inhibitor complex, leucine-rich repeat, enzyme-inhibitor complex, structural genomics, protein structure initiative, psi, center for eukaryotic structural genomics, cesg, hydrolase-hydrolase inhibitor complex, hydrolase/hydrolase inhibitor
• 由来する生物種: Homo sapiens (human); 詳細
• 細胞内の位置: Secreted: P07998; Cytoplasm: P13489
• タンパク質・核酸の鎖数: 4
• 化学式量合計: 129686.03

構造登録者

Levin, E.J.,Kondrashov, D.A.,Wesenberg, G.E.,Phillips Jr., G.N.,Center for Eukaryotic Structural Genomics (CESG) (登録日: 2007-05-31, 公開日: 2007-06-19, 最終更新日: 2024-10-16)

主引用文献

Johnson, R.J.,McCoy, J.G.,Bingman, C.A.,Phillips Jr., G.N.,Raines, R.T.
Inhibition of human pancreatic ribonuclease by the human ribonuclease inhibitor protein.
J.Mol.Biol., 368:434-449, 2007

PubMed Abstract: The ribonuclease inhibitor protein (RI) binds to members of the bovine pancreatic ribonuclease (RNase A) superfamily with an affinity in the femtomolar range. Here, we report on structural and energetic aspects of the interaction between human RI (hRI) and human pancreatic ribonuclease (RNase 1). The structure of the crystalline hRI x RNase 1 complex was determined at a resolution of 1.95 A, revealing the formation of 19 intermolecular hydrogen bonds involving 13 residues of RNase 1. In contrast, only nine such hydrogen bonds are apparent in the structure of the complex between porcine RI and RNase A. hRI, which is anionic, also appears to use its horseshoe-shaped structure to engender long-range Coulombic interactions with RNase 1, which is cationic. In accordance with the structural data, the hRI.RNase 1 complex was found to be extremely stable (t(1/2)=81 days; K(d)=2.9 x 10(-16) M). Site-directed mutagenesis experiments enabled the identification of two cationic residues in RNase 1, Arg39 and Arg91, that are especially important for both the formation and stability of the complex, and are thus termed "electrostatic targeting residues". Disturbing the electrostatic attraction between hRI and RNase 1 yielded a variant of RNase 1 that maintained ribonucleolytic activity and conformational stability but had a 2.8 x 10(3)-fold lower association rate for complex formation and 5.9 x 10(9)-fold lower affinity for hRI. This variant of RNase 1, which exhibits the largest decrease in RI affinity of any engineered ribonuclease, is also toxic to human erythroleukemia cells. Together, these results provide new insight into an unusual and important protein-protein interaction, and could expedite the development of human ribonucleases as chemotherapeutic agents.

PubMed: 17350650
DOI: 10.1016/j.jmb.2007.02.005

実験手法

X-RAY DIFFRACTION (1.954 Å)