Cloning, crystallization and preliminary X-ray study of XC1258, a CN-hydrolase superfamily protein from Xanthomonas campestris.

CN-hydrolase superfamily proteins are involved in a wide variety of non-peptide carbon-nitrogen hydrolysis reactions, producing some important natural products such as auxin, biotin, precursors of antibiotics etc. These reactions all involve attack on a cyano or carbonyl carbon by a conserved novel catalytic triad Glu-Lys-Cys through a thiol acylenzyme intermediate. However, classification into the CN-hydrolase superfamily based on sequence similarity alone is not straightforward and further structural data are necessary to improve this categorization. Here, the cloning, expression, crystallization and preliminary X-ray analysis of XC1258, a CN-hydrolase superfamily protein from the plant pathogen Xanthomonas campestris (Xcc), are reported. The SeMet-substituted XC1258 crystals diffracted to a resolution of 1.73 A. They are orthorhombic and belong to space group P2(1)2(1)2, with unit-cell parameters a = 143.8, b = 154.63, c = 51.3 A, respectively.