PDBsum entry: 1oz0

Transferase, hydrolase

PDB id: 1oz0

Contents

Protein chains

590 a.a. *

Ligands

PO4 ×2

MS1 ×2

Metals

__K ×2

Waters ×378

* Residue conservation analysis

PDB id:

1oz0

Name:

Transferase, hydrolase

Title:

Crystal structure of the homodimeric bifunctional transformylase and cyclohydrolase enzyme avian atic in complex with a multisubstrate adduct inhibitor beta-dadf.

Structure:

Bifunctional purine biosynthesis protein purh. Chain: a, b. Synonym: aicar transformylase-imp cyclohydrolase, phosphoribosylaminoimidazolecarboxamide formyltransferase, inosinicase, imp synthetase, atic. Engineered: yes

Source:

Gallus gallus. Chicken. Organism_taxid: 9031. Gene: atic or purh. Expressed in: escherichia coli bl21(de3). Expression_system_taxid: 469008.

Biol. unit:

Dimer (from PQS)

Resolution:

2.50Å R-factor: 0.217 R-free: 0.269

Authors:

D.W.Wolan,S.E.Greasley,M.J.Wall,S.J.Benkovic,I.A.Wilson

Key ref:

D.W.Wolan et al. (2003). Structure of avian AICAR transformylase with a multisubstrate adduct inhibitor beta-DADF identifies the folate binding site. Biochemistry, 42, 10904-10914. PubMed id: 12974624 DOI: 10.1021/bi030106h

Date:

07-Apr-03 Release date: 30-Sep-03

Protein chains

P31335  (PUR9_CHICK) -  Bifunctional purine biosynthesis protein PURH

Seq: 593 a.a.

Struc: 590 a.a.

Enzyme reactions

• Enzyme class 2: E.C.2.1.2.3 - Phosphoribosylaminoimidazolecarboxamide formyltransferase.
• Pathway: Purine Biosynthesis (late stages)
• Reaction: 10-formyltetrahydrofolate + 5-amino-1-(5-phospho-D-ribosyl)imidazole-4- carboxamide = tetrahydrofolate + 5-formamido-1-(5-phospho-D- ribosyl)imidazole-4-carboxamide

10-formyltetrahydrofolate (Bound ligand (Het Group name = MS1) matches with 56.00% similarity) + 5-amino-1-(5-phospho-D-ribosyl)imidazole-4- carboxamide = tetrahydrofolate + 5-formamido-1-(5-phospho-D- ribosyl)imidazole-4-carboxamide

• Enzyme class 3: E.C.3.5.4.10 - Imp cyclohydrolase.

Pathway:

• Reaction: IMP + H₂O = 5-formamido-1-(5-phospho-D-ribosyl)imidazole-4-carboxamide

Note, where more than one E.C. class is given (as above), each may correspond to a different protein domain or, in the case of polyprotein precursors, to a different mature protein.

Molecule diagrams generated from .mol files obtained from the KEGG ftp site

 Gene Ontology (GO) functional annotation 

• Cellular component: mitochondrion (1 term)
• Biological process: metabolic process (3 terms)
• Biochemical function: catalytic activity (6 terms)

reference

DOI no: 10.1021/bi030106h

Biochemistry 42:10904-10914 (2003)

PubMed id: 12974624

Structure of avian AICAR transformylase with a multisubstrate adduct inhibitor beta-DADF identifies the folate binding site.

D.W.Wolan, S.E.Greasley, M.J.Wall, S.J.Benkovic, I.A.Wilson.

ABSTRACT

The penultimate catalytic step of the purine de novo synthesis pathway is the conversion of aminoimidazole-4-carboxamide ribonucleotide (AICAR) to 5-formyl-AICAR that requires the cofactor N(10)-formyl-tetrahydrofolate as the formyl donor. This reaction is catalyzed by the AICAR transformylase domain of the bifunctional enzyme AICAR transformylase/inosine monophosphate cyclohydrolase (ATIC). Identification of the location of the AICAR transformylase active site was previously elucidated from the crystal structure of the avian ATIC with bound substrate AICAR; however, due to the absence of any bound folate, the folate binding region of the active site could not be identified. Here, we have determined the homodimeric crystal structure of avian ATIC in complex with the ATIC-specific multisubstrate adduct inhibitor beta-DADF to 2.5 A resolution. Beta-DADF encompasses both the AICAR and folate moieties into a single covalently linked entity, thereby allowing for the characterization of the folate binding pocket of the AICAR transformylase active site. Beta-DADF is intimately bound at the dimer interface of the transformylase domains with the majority of AICAR moiety interactions occurring within one subunit, whereas the primary interactions to the folate occur with the opposing subunit. The crystal structure suggests that a buried Lys(267) is transiently protonated during formyl transfer allowing for the stabilization of the oxyanion transition state and subsequent protonation of N10 on the tetrahydrofolate leaving group. Furthermore, the beta-DADF-bound structure provides a more optimal three-dimensional scaffold to improve the design of specific antineoplastic agents.