1gsa
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STRUCTURE OF GLUTATHIONE SYNTHETASE COMPLEXED WITH ADP AND GLUTATHIONE
OverviewOverview
The crystal structure of glutathione synthetase from Escherichia coli B, complexed with ADP, glutathione, and sulfate has been determined at 2.0 A, resolution. Concerning the chemical similarity of sulfate and phosphate, this quaternary complex structure represents a pseudo enzyme-substrate, complex in the reverse reaction and consequently allows us to understand, the active site architecture of the E. coli glutathione synthetase. Two, Mg2+ ions are coordinated with oxygen atoms from the alpha- and, beta-phosphate groups of ADP and from the sulfate ion. The flexible loops, invisible in the unliganded or the binary and ternary complex structures, are fixed in the quaternary complex. The larger flexible loop, (Ile226-Arg241) includes one turn of a 310-helix that comprises the, binding site of the glycine moiety of GSH. The small loop (Gly164-Gly167), is involved in nucleotide binding and acts as a phosphate gripper. The, side chains of Arg210 and Arg225 interact with the sulfate ion and the, beta-phosphate moiety of ADP. Arg 210 is likely to interact with the, carboxylate of the C-terminal gamma-glutamylcysteine in the, substrate-binding form of the forward reaction. Other positively charged, residues in the active site (Lys125 and Lys160) are involved in nucleotide, binding, directing the phosphate groups to the right position for, catalysis. Functional aspects of the active site architecture in the, substrate-binding form are discussed.
About this StructureAbout this Structure
1GSA is a Single protein structure of sequence from Escherichia coli with MG, SO4, ADP and GTT as ligands. Active as Glutathione synthase, with EC number 6.3.2.3 Full crystallographic information is available from OCA.
ReferenceReference
A pseudo-michaelis quaternary complex in the reverse reaction of a ligase: structure of Escherichia coli B glutathione synthetase complexed with ADP, glutathione, and sulfate at 2.0 A resolution., Hara T, Kato H, Katsube Y, Oda J, Biochemistry. 1996 Sep 17;35(37):11967-74. PMID:8810901
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