2ab8

From Proteopedia

Crystal structure of T. gondii adenosine kinase complexed with 6-methylmercaptopurine riboside and AMP-PCP

PDB ID 2ab8

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Structural highlights

2ab8 is a 1 chain structure with sequence from Toxoplasma gondii. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:	X-ray diffraction, Resolution 1.75Å
Ligands:	, , ,
Resources:	FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

ADK_TOXGO ATP-dependent phosphorylation of adenosine and other related nucleoside analogs to monophosphate derivatives. It is a key purine metabolic enzyme in the opportunistic parasitic protozoan toxoplasma gondii as it cannot synthesize purines de novo.

Evolutionary Conservation

Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.

Publication Abstract from PubMed

Adenosine kinase (AK) is a key enzyme in purine metabolism in the ubiquitous intracellular parasite Toxoplasma gondii and is a potential chemotherapeutic target for the treatment of T. gondii infections. To better understand the structure-activity relationship of 6-substituted purine ribosides, the structures of the T. gondii AK-N6,N6-dimethyladenosine (DMA) complex, the AK-DMA-AMP-PCP complex, the AK-6-methyl mercaptopurine riboside (MMPR) complex and the AK-MMPR-AMP-PCP complex were determined to 1.35, 1.35, 1.75 and 1.75 A resolution, respectively. These structures reveal a conformation intermediate between open and closed, with a small lid-domain rotation of 12 degrees . Residues Gly143-X-X-Gly146 undergo torsional changes upon substrate binding, which together with a Gly68-Gly69 switch induces a hinge bending of the lid domain. The intermediate conformation suggests that ATP binding is independent of adenosine binding. Orienting the gamma-phosphate group of ATP into the optimal catalytic position may be the last step before the onset of chemical catalysis and may require the translocation of Arg136 following the complete closure of the lid domain. 6-Substituted purine-nucleoside analogs are accommodated in a hydrophobic cavity. Modification at the N6 or C6 position of the nucleoside would affect the interactions with the surrounding residues and the binding affinity.

Substrate analogs induce an intermediate conformational change in Toxoplasma gondii adenosine kinase.,Zhang Y, El Kouni MH, Ealick SE Acta Crystallogr D Biol Crystallogr. 2007 Feb;63(Pt 2):126-34. Epub 2007, Jan 16. PMID:17242506^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

References

↑ Zhang Y, El Kouni MH, Ealick SE. Substrate analogs induce an intermediate conformational change in Toxoplasma gondii adenosine kinase. Acta Crystallogr D Biol Crystallogr. 2007 Feb;63(Pt 2):126-34. Epub 2007, Jan 16. PMID:17242506 doi:10.1107/S0907444906043654