Steve Ealick's Research Group

Escherichia coli N5-carboxyaminoimidazole Ribonucleotide Mutase

PDB files:

1QCZ (native PurE)

1D7A (PurE complexed with AIR)

*2ATE (PurE complexed with nitro-AIR)

*2NSH, E. coli PurE H45Q mutant complexed with nitro-AIR

*2NSJ, E. coli PurE H45Q mutant complexed with CAIR

*2NSL, E. coli PurE H45N mutant complexed with CAIR


The crystal structure of PurE, which is the mutase that catalyzes the rearrangement of N5-carboxyaminoimidazole ribonucleotide (N5-CAIR) to 4-carboxyaminoimidazole
ribonucleotide (CAIR), has been determined to 1.50 Å and found to have octameric structure. PurEs from higher eukaryotes are homologous to E. coli PurE, but use aminoimidazole ribonucleotide (AIR)and CO2 as substrates to produce CAIR directly.

A central three-layer (αβα) sandwich domain and a kinked C-terminal helix form the folded structure of the monomeric unit. The monomers are identical 17 kDa subunits

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The monomers are arranged in an octameric structure with 422 symmetry. Here the octomer is viewed down the four-fold axis.

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The left side of the graphic shows the wild type E. coli PurE active site bound to NO2-AIR, while the left site is the mutant H45Q EcPurE active site bound to CAIR.

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Mathews II, Kappock TJ, Stubbe J and Ealick S. Crystal structure of Escherichia coli PurE, an unusual mutase in the purine biosynthetic pathway. Structure 7:1395-1406 (1999).

*Hoskins AA, Morar Mariya M, Kappock TJ, Mathews II, Zaugg JB, Barder TE, Peng P, Okamoto A, Ealick SE, and Stubbe J. N5-CAIR Mutase: the role of a CO2 binding site and substrate movement in catalysis. Biochemistry 46:2846-2855 (2007).

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