3ijf | pdb_00003ijf
Crystal structure of cytidine deaminase from Mycobacterium tuberculosis
Structural highlights
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 PubMedThe emergence of drug-resistant strains of Mycobacterium tuberculosis, the causative agent of tuberculosis, has exacerbated the treatment and control of this disease. Cytidine deaminase (CDA) is a pyrimidine salvage pathway enzyme that recycles cytidine and 2'-deoxycytidine for uridine and 2'-deoxyuridine synthesis, respectively. A probable M. tuberculosis CDA-coding sequence (cdd, Rv3315c) was cloned, sequenced, expressed in Escherichia coli BL21(DE3), and purified to homogeneity. Mass spectrometry, N-terminal amino acid sequencing, gel filtration chromatography, and metal analysis of M. tuberculosis CDA (MtCDA) were carried out. These results and multiple sequence alignment demonstrate that MtCDA is a homotetrameric Zn(2+)-dependent metalloenzyme. Steady-state kinetic measurements yielded the following parameters: K(m)=1004 microM and k(cat)=4.8s(-1) for cytidine, and K(m)=1059 microM and k(cat)=3.5s(-1) for 2'-deoxycytidine. The pH dependence of k(cat) and k(cat)/K(M) for cytidine indicate that protonation of a single ionizable group with apparent pK(a) value of 4.3 abolishes activity, and protonation of a group with pK(a) value of 4.7 reduces binding. MtCDA was crystallized and crystal diffracted at 2.0 A resolution. Analysis of the crystallographic structure indicated the presence of a Zn(2+) coordinated by three conserved cysteines and the structure exhibits the canonical cytidine deaminase fold. Structural and functional analyses of Mycobacterium tuberculosis Rv3315c-encoded metal-dependent homotetrameric cytidine deaminase.,Sanchez-Quitian ZA, Schneider CZ, Ducati RG, de Azevedo WF Jr, Bloch C Jr, Basso LA, Santos DS J Struct Biol. 2010 Mar;169(3):413-23. Epub 2009 Dec 24. PMID:20035876[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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