View source for 1jtk

[[Image:1jtk.gif|left|200px]]<br /><applet load="1jtk" size="350" color="white" frame="true" align="right" spinBox="true" 
caption="1jtk, resolution 2.04&Aring;" />
'''Crystal structure of cytidine deaminase from Bacillus subtilis in complex with the inhibitor tetrahydrodeoxyuridine'''<br />

==Overview==
Cytidine deaminases (CDA, EC 3.5.4.5) are zinc-containing enzymes in the pyrimidine salvage pathway that catalyze the formation of uridine and deoxyuridine from cytidine and deoxycytidine, respectively. Two different classes have been identified in the CDA family, a homodimeric form (D-CDA) with two zinc ions per dimer and a homotetrameric form (T-CDA) with four zinc ions per tetramer. We have determined the first structure of a T-CDA from Bacillus subtilis. The active form of T-CDA is assembled of four identical subunits with one active site apiece. The subunit of D-CDA is composed of two domains each exhibiting the same fold as the T-CDA subunits, but only one of them contains zinc in the active site. The similarity results in a conserved structural core in the two CDA forms. An intriguing difference between the two CDA structures is the zinc coordinating residues found at the N-terminal of two alpha-helices: three cysteine residues in the tetrameric form and two cysteine residues and one histidine residue in the dimeric form. The role of the zinc ion is to activate a water molecule and thereby generate a hydroxide ion. How the zinc ion in T-CDA surrounded with three negatively charged residues can create a similar activity of T-CDA compared to D-CDA has been an enigma. However, the structure of T-CDA reveals that the negative charge caused by the three ligands is partly neutralized by (1) an arginine residue hydrogen-bonded to two of the cysteine residues and (2) the dipoles of two alpha-helices.

==About this Structure==
1JTK is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Bacillus_subtilis Bacillus subtilis] with <scene name='pdbligand=ZN:'>ZN</scene> and <scene name='pdbligand=THU:'>THU</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Cytidine_deaminase Cytidine deaminase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.5.4.5 3.5.4.5] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1JTK OCA]. 

==Reference==
Crystal structure of the tetrameric cytidine deaminase from Bacillus subtilis at 2.0 A resolution., Johansson E, Mejlhede N, Neuhard J, Larsen S, Biochemistry. 2002 Feb 26;41(8):2563-70. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=11851403 11851403]
[[Category: Bacillus subtilis]]
[[Category: Cytidine deaminase]]
[[Category: Single protein]]
[[Category: Johansson, E.]]
[[Category: Larsen, S.]]
[[Category: Mejlhede, N.]]
[[Category: Neuhard, J.]]
[[Category: THU]]
[[Category: ZN]]
[[Category: cda]]
[[Category: cytidine deaminase]]
[[Category: pyrimidine salvage pathway]]
[[Category: zinc]]

''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 13:26:36 2008''