1ez1

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spinqualitylabelsall models 1ez1, resolution 1.75Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

STRUCTURE OF ESCHERICHIA COLI PURT-ENCODED GLYCINAMIDE RIBONUCLEOTIDE TRANSFORMYLASE COMPLEXED WITH MG, AMPPNP, AND GAR

Overview

In Escherichia coli, the PurT-encoded glycinamide ribonucleotide, transformylase, or PurT transformylase, catalyzes an alternative, formylation of glycinamide ribonucleotide (GAR) in the de novo pathway for, purine biosynthesis. On the basis of amino acid sequence analyses, it is, known that the PurT transformylase belongs to the ATP-grasp superfamily of, proteins. The common theme among members of this superfamily is a, catalytic reaction mechanism that requires ATP and proceeds through an, acyl phosphate intermediate. All of the enzymes belonging to the ATP-grasp, superfamily are composed of three structural motifs, termed the A-, B-, and C-domains, and in each case, the ATP is wedged between the B- and, C-domains. Here we describe two high-resolution X-ray crystallographic, structures of PurT transformylase from E. coli: one form complexed with, the nonhydrolyzable ATP analogue AMPPNP and the second with bound AMPPNP, and GAR. The latter structure is of special significance because it, represents the first ternary complex to be determined for a member of the, ATP-grasp superfamily involved in purine biosynthesis and as such provides, new information about the active site region involved in ribonucleotide, binding. Specifically in PurT transformylase, the GAR substrate is, anchored to the protein via Glu 82, Asp 286, Lys 355, Arg 362, and Arg, 363. Key amino acid side chains involved in binding the AMPPNP to the, enzyme include Arg 114, Lys 155, Glu 195, Glu 203, and Glu 267., Strikingly, the amino group of GAR that is formylated during the reaction, lies at 2.8 A from one of the gamma-phosphoryl oxygens of the AMPPNP.

About this Structure

1EZ1 is a Single protein structure of sequence from Escherichia coli with MG, ACT, NA, ANP, GAR and MPO as ligands. Full crystallographic information is available from OCA.

Reference

Molecular structure of Escherichia coli PurT-encoded glycinamide ribonucleotide transformylase., Thoden JB, Firestine S, Nixon A, Benkovic SJ, Holden HM, Biochemistry. 2000 Aug 1;39(30):8791-802. PMID:10913290

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