3T8L

Crystal Structure of adenine deaminase with Mn/Fe

Summary for 3T8L

• Entry DOI: 10.2210/pdb3t8l/pdb
• Related: 3NQB 3T81
• Descriptor: Adenine deaminase 2, UNKNOWN ATOM OR ION (3 entities in total)
• Functional Keywords: psi-2, structural genomics, protein structure initiative, new york sgx research center for structural genomics, nysgxrc, amidohydrolase, nucleotide binding, hydrolase, tim barrel, alpha/beta, adenine deaminase, adenine
• Biological source: Agrobacterium tumefaciens
• Total number of polymer chains: 2
• Total formula weight: 130138.73

Authors

Bagaria, A.,Kumaran, D.,Burley, S.K.,Swaminathan, S.,New York SGX Research Center for Structural Genomics (NYSGXRC) (deposition date: 2011-08-01, release date: 2011-11-02, Last modification date: 2024-11-27)

Primary citation

Kamat, S.S.,Holmes-Hampton, G.P.,Bagaria, A.,Kumaran, D.,Tichy, S.E.,Gheyi, T.,Zheng, X.,Bain, K.,Groshong, C.,Emtage, S.,Sauder, J.M.,Burley, S.K.,Swaminathan, S.,Lindahl, P.A.,Raushel, F.M.
The catalase activity of diiron adenine deaminase.
Protein Sci., 20:2080-2094, 2011

PubMed Abstract: Adenine deaminase (ADE) from the amidohydrolase superfamily (AHS) of enzymes catalyzes the conversion of adenine to hypoxanthine and ammonia. Enzyme isolated from Escherichia coli was largely inactive toward the deamination of adenine. Molecular weight determinations by mass spectrometry provided evidence that multiple histidine and methionine residues were oxygenated. When iron was sequestered with a metal chelator and the growth medium supplemented with Mn(2+) before induction, the post-translational modifications disappeared. Enzyme expressed and purified under these conditions was substantially more active for adenine deamination. Apo-enzyme was prepared and reconstituted with two equivalents of FeSO(4). Inductively coupled plasma mass spectrometry and Mössbauer spectroscopy demonstrated that this protein contained two high-spin ferrous ions per monomer of ADE. In addition to the adenine deaminase activity, [Fe(II) /Fe(II) ]-ADE catalyzed the conversion of H(2)O(2) to O(2) and H(2)O. The values of k(cat) and k(cat)/K(m) for the catalase activity are 200 s(-1) and 2.4 × 10(4) M(-1) s(-1), respectively. [Fe(II)/Fe(II)]-ADE underwent more than 100 turnovers with H(2)O(2) before the enzyme was inactivated due to oxygenation of histidine residues critical for metal binding. The iron in the inactive enzyme was high-spin ferric with g(ave) = 4.3 EPR signal and no evidence of anti-ferromagnetic spin-coupling. A model is proposed for the disproportionation of H(2)O(2) by [Fe(II)/Fe(II)]-ADE that involves the cycling of the binuclear metal center between the di-ferric and di-ferrous oxidation states. Oxygenation of active site residues occurs via release of hydroxyl radicals. These findings represent the first report of redox reaction catalysis by any member of the AHS.

PubMed: 21998098
DOI: 10.1002/pro.748

Experimental method

X-RAY DIFFRACTION (2.8 Å)