3A9Z

Crystal structure of ras selenocysteine lyase in complex with selenopropionate

3A9Z の概要

• エントリーDOI: 10.2210/pdb3a9z/pdb
• 関連するPDBエントリー: 3A9X 3A9Y
• 分子名称: Selenocysteine lyase, PYRIDOXAL-5'-PHOSPHATE, 3-selanylpropanoic acid, ... (5 entities in total)
• 機能のキーワード: selenocysteine, plp, lyase, pyridoxal phosphate, transferase
• 由来する生物種: Rattus norvegicus (brown rat,rat,rats)
• 細胞内の位置: Cytoplasm, cytosol (By similarity): Q68FT9
• タンパク質・核酸の鎖数: 2
• 化学式量合計: 95615.82

構造登録者

Omi, R.,Hirotsu, K. (登録日: 2009-11-09, 公開日: 2010-03-16, 最終更新日: 2013-10-30)

主引用文献

Omi, R.,Kurokawa, S.,Mihara, H.,Hayashi, H.,Goto, M.,Miyahara, I.,Kurihara, T.,Hirotsu, K.,Esaki, N.
Reaction mechanism and molecular basis for selenium/sulfur discrimination of selenocysteine lyase.
J.Biol.Chem., 285:12133-12139, 2010

PubMed Abstract: Selenocysteine lyase (SCL) catalyzes the pyridoxal 5'-phosphate-dependent removal of selenium from l-selenocysteine to yield l-alanine. The enzyme is proposed to function in the recycling of the micronutrient selenium from degraded selenoproteins containing selenocysteine residue as an essential component. The enzyme exhibits strict substrate specificity toward l-selenocysteine and no activity to its cognate l-cysteine. However, it remains unclear how the enzyme distinguishes between selenocysteine and cysteine. Here, we present mechanistic studies of selenocysteine lyase from rat. ESI-MS analysis of wild-type and C375A mutant SCL revealed that the catalytic reaction proceeds via the formation of an enzyme-bound selenopersulfide intermediate on the catalytically essential Cys-375 residue. UV-visible spectrum analysis and the crystal structure of SCL complexed with l-cysteine demonstrated that the enzyme reversibly forms a nonproductive adduct with l-cysteine. Cys-375 on the flexible loop directed l-selenocysteine, but not l-cysteine, to the correct position and orientation in the active site to initiate the catalytic reaction. These findings provide, for the first time, the basis for understanding how trace amounts of a selenium-containing substrate is distinguished from excessive amounts of its cognate sulfur-containing compound in a biological system.

PubMed: 20164179
DOI: 10.1074/jbc.M109.084475

実験手法

X-RAY DIFFRACTION (1.55 Å)