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

Description:

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

Click the image to enlarge.

 

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

Click the image to enlarge.

 

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.

Click the image to enlarge.

Reference:

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).



Contacts Procedures Structures Projects Publications Lab Home Page Group Members