Expression, crystallization and preliminary crystallographic studies of a novel bifunctional N-acetylglutamate synthase/kinase from Xanthomonas campestris homologous to vertebrate N-acetylglutamate synthase.

A novel N-acetylglutamate synthase/kinase bifunctional enzyme of arginine biosynthesis that was homologous to vertebrate N-acetylglutamate synthases was identified in Xanthomonas campestris. The protein was overexpressed, purified and crystallized. The crystals belong to the hexagonal space group P6(2)22, with unit-cell parameters a = b = 134.60, c = 192.11 A, and diffract to about 3.0 A resolution. Selenomethionine-substituted recombinant protein was produced and selenomethionine substitution was verified by mass spectroscopy. Multiple anomalous dispersion (MAD) data were collected at three wavelengths at SER-CAT, Advanced Photon Source, Argonne National Laboratory. Structure determination is under way using the MAD phasing method.