Structure and mechanism of glutamate racemase from Aquifex pyrophilus.
Glutamate racemase (MurI) is responsible for the synthesis of D-glutamate, an essential building block of the peptidoglycan layer in bacterial cell walls. The crystal structure of glutamate racemase from Aquifex pyrophilus, determined at 2.3 A resolution, reveals that the enzyme forms a dimer and each monomer consists of two alpha/beta fold domains, a unique structure that has not been observed in other racemases or members of an enolase superfamily. A substrate analog, D-glutamine, binds to the deep pocket formed by conserved residues from two monomers. The structural and mutational analyses allow us to propose a mechanism of metal cofactor-independent glutamate racemase in which two cysteine residues are involved in catalysis.
Hwang
K Y
KY
Structural Biology Center, Korea Institute of Science and Technology, Seoul, South Korea.
Cho
C S
CS
Kim
S S
SS
Sung
H C
HC
Yu
Y G
YG
Cho
Y
Y
D000591:Amino Acid Isomerases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001051:Apoenzymes / Q000737:chemistry / Q000378:metabolism; D001665:Binding Sites; D002384:Catalysis; D018360:Crystallography, X-Ray; D003545:Cysteine / Q000737:chemistry / Q000378:metabolism; D019281:Dimerization; D005973:Glutamine / Q000737:chemistry / Q000378:metabolism; D016946:Gram-Negative Aerobic Rods and Cocci / Q000201:enzymology* / Q000235:genetics; D007700:Kinetics; D008956:Models, Chemical; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010751:Phosphopyruvate Hydratase / Q000737:chemistry; D011485:Protein Binding; D011487:Protein Conformation; D017433:Protein Structure, Secondary
D001051:Apoenzymes; D005973:Glutamine; D010751:Phosphopyruvate Hydratase; D000591:Amino Acid Isomerases; C062292:glutamate racemase; D003545:Cysteine