1DET

RIBONUCLEASE T1 CARBOXYMETHYLATED AT GLU 58 IN COMPLEX WITH 2'GMP

1DET の概要

• エントリーDOI: 10.2210/pdb1det/pdb
• 分子名称: RIBONUCLEASE T1, SODIUM ION, GUANOSINE-2'-MONOPHOSPHATE, ... (4 entities in total)
• 機能のキーワード: hydrolase, endoribonuclease, nuclease, endonuclease, hydrolase (endoribonuclease)
• 由来する生物種: Aspergillus oryzae
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 11560.88

構造登録者

Ishikawa, K.,Suzuki, E.,Tanokura, M.,Takahashi, K. (登録日: 1996-02-20, 公開日: 1996-07-11, 最終更新日: 2024-06-05)

主引用文献

Ishikawa, K.,Suzuki, E.,Tanokura, M.,Takahashi, K.
Crystal structure of ribonuclease T1 carboxymethylated at Glu58 in complex with 2'-GMP.
Biochemistry, 35:8329-8334, 1996

PubMed Abstract: The carboxymethylation of RNase T1 at the gamma-carboxyl group of Glu58 leads to a complete loss of the enzymatic activity while it retains substrate-binding ability. Accompanying the carboxymethylation, RNase T1 undergoes a remarkable thermal stabilization of 9 degrees C in the melting temperature (Tm). In order to clarify the inactivation and stabilization mechanisms of RNase T1 by carboxymethylation, the crystal structure of carboxymethylated RNase T1 (CM-RNase T1) complexed with 2'-GMP was determined at 1.8 A resolution. The structure, including 79 water molecules and two Na+, was refined to an R factor of 0.194 with 10 354 reflections > 1 sigma (F). The carboxyl group of CM-Glu58, which locates in the active site, occupies almost the same position as the phosphate group of 2'-GMP in the crystal structure of intact RNase T1.2'-GMP complex. Therefore, the phosphate group of 2'-GMP cannot locate in the active site but protrudes toward the solvent. This forces 2'-GMP to adopt an anti form, which contrasts with the syn form in the crystal of the intact RNase T1.2'-GMP complex. The inaccessibility of the phosphate group to the active site can account for the lack of the enzymatic activity in CM-RNase T1. One of the carboxyl oxygen atoms of CM-Glu58 forms two hydrogen bonds with the side-chains of Tyr38 and His40. These hydrogen bonds are considered to mainly contribute to the higher thermal stability of CM-RNase T1. Another carboxyl oxygen atoms of CM-Glu58 is situated nearby His40 and Arg77. This may provide additional electrostatic stabilization.

PubMed: 8679590
DOI: 10.1021/bi960493d

実験手法

X-RAY DIFFRACTION (1.8 Å)