3A9Z
Crystal structure of ras selenocysteine lyase in complex with selenopropionate
Summary for 3A9Z
| Entry DOI | 10.2210/pdb3a9z/pdb |
| Related | 3A9X 3A9Y |
| Descriptor | Selenocysteine lyase, PYRIDOXAL-5'-PHOSPHATE, 3-selanylpropanoic acid, ... (5 entities in total) |
| Functional Keywords | selenocysteine, plp, lyase, pyridoxal phosphate, transferase |
| Biological source | Rattus norvegicus (brown rat,rat,rats) |
| Cellular location | Cytoplasm, cytosol (By similarity): Q68FT9 |
| Total number of polymer chains | 2 |
| Total formula weight | 95615.82 |
| Authors | Omi, R.,Hirotsu, K. (deposition date: 2009-11-09, release date: 2010-03-16, Last modification date: 2013-10-30) |
| Primary citation | 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 Cited by 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: 20164179DOI: 10.1074/jbc.M109.084475 PDB entries with the same primary citation |
| Experimental method | X-RAY DIFFRACTION (1.55 Å) |
Structure validation
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