4A5A

Crystal structure of the C258S/C268S variant of Toxoplasma gondii nucleoside triphosphate diphosphohydrolase 3 (NTPDase3) in complex with magnesium and AMPPNP

Summary for 4A5A

• Entry DOI: 10.2210/pdb4a5a/pdb
• Related: 4A57 4A59 4A5B
• Descriptor: NUCLEOSIDE-TRIPHOSPHATASE 1, PHOSPHOAMINOPHOSPHONIC ACID-ADENYLATE ESTER, MAGNESIUM ION (3 entities in total)
• Functional Keywords: hydrolase, ntpdase
• Biological source: TOXOPLASMA GONDII
• Cellular location: Secreted: Q27893
• Total number of polymer chains: 4
• Total formula weight: 272625.16

Authors

Krug, U.,Zebisch, M.,Straeter, N. (deposition date: 2011-10-24, release date: 2011-11-30, Last modification date: 2024-11-06)

Primary citation

Krug, U.,Zebisch, M.,Krauss, M.,Straeter, N.
Structural Insight Into the Activation Mechanism of Toxoplasma Gondii Nucleoside Triphosphate Diphosphohydrolases by Disulfide Reduction.
J.Biol.Chem., 287:3051-, 2012

PubMed Abstract: The intracellular parasite Toxoplasma gondii produces two nucleoside triphosphate diphosphohydrolases (NTPDase1 and -3). These tetrameric, cysteine-rich enzymes require activation by reductive cleavage of a hitherto unknown disulfide bond. Despite a 97% sequence identity, both isozymes differ largely in their ability to hydrolyze ATP and ADP. Here, we present crystal structures of inactive NTPDase3 as an apo form and in complex with the product AMP to resolutions of 2.0 and 2.2 Å, respectively. We find that the enzyme is present in an open conformation that precludes productive substrate binding and catalysis. The cysteine bridge 258-268 is identified to be responsible for locking of activity. Crystal structures of constitutively active variants of NTPDase1 and -3 generated by mutation of Cys(258)-Cys(268) show that opening of the regulatory cysteine bridge induces a pronounced contraction of the whole tetramer. This is accompanied by a 12° domain closure motion resulting in the correct arrangement of all active site residues. A complex structure of activated NTPDase3 with a non-hydrolyzable ATP analog and the cofactor Mg(2+) to a resolution of 2.85 Å indicates that catalytic differences between the NTPDases are primarily dictated by differences in positioning of the adenine base caused by substitution of Arg(492) and Glu(493) in NTPDase1 by glycines in NTPDase3.

PubMed: 22130673
DOI: 10.1074/JBC.M111.294348

Experimental method

X-RAY DIFFRACTION (2.85 Å)