3IG5

Saccharomyces cerevisiae glutamate cysteine ligase in complex with Mg2+ and L-glutamate

Summary for 3IG5

• Entry DOI: 10.2210/pdb3ig5/pdb
• Related: 3IG8
• Descriptor: Glutamate-cysteine ligase, GLUTAMIC ACID, MAGNESIUM ION, ... (5 entities in total)
• Functional Keywords: ligase, glutathione, atp-grasp, atp-binding, glutathione biosynthesis, nucleotide-binding, phosphoprotein
• Biological source: Saccharomyces cerevisiae (brewer's yeast,lager beer yeast,yeast)
• Total number of polymer chains: 1
• Total formula weight: 80713.33

Authors

Biterova, E.,Barycki, J.J. (deposition date: 2009-07-27, release date: 2009-09-01, Last modification date: 2024-11-27)

Primary citation

Biterova, E.I.,Barycki, J.J.
Mechanistic details of glutathione biosynthesis revealed by crystal structures of Saccharomyces cerevisiae glutamate cysteine ligase.
J.Biol.Chem., 284:32700-32708, 2009

PubMed Abstract: Glutathione is a thiol-disulfide exchange peptide critical for buffering oxidative or chemical stress, and an essential cofactor in several biosynthesis and detoxification pathways. The rate-limiting step in its de novo biosynthesis is catalyzed by glutamate cysteine ligase, a broadly expressed enzyme for which limited structural information is available in higher eukaryotic species. Structural data are critical to the understanding of clinical glutathione deficiency, as well as rational design of enzyme modulators that could impact human disease progression. Here, we have determined the structures of Saccharomyces cerevisiae glutamate cysteine ligase (ScGCL) in the presence of glutamate and MgCl(2) (2.1 A; R = 18.2%, R(free) = 21.9%), and in complex with glutamate, MgCl(2), and ADP (2.7 A; R = 19.0%, R(free) = 24.2%). Inspection of these structures reveals an unusual binding pocket for the alpha-carboxylate of the glutamate substrate and an ATP-independent Mg(2+) coordination site, clarifying the Mg(2+) dependence of the enzymatic reaction. The ScGCL structures were further used to generate a credible homology model of the catalytic subunit of human glutamate cysteine ligase (hGCLC). Examination of the hGCLC model suggests that post-translational modifications of cysteine residues may be involved in the regulation of enzymatic activity, and elucidates the molecular basis of glutathione deficiency associated with patient hGCLC mutations.

PubMed: 19726687
DOI: 10.1074/jbc.M109.025114

Experimental method

X-RAY DIFFRACTION (2.1 Å)