title: Preliminary X-ray crystallographic analysis of the secreted chorismate mutase from Mycobacterium tuberculosis: a tricky crystallization problem solved.
abstract: Chorismate mutase catalyzes the conversion of chorismate to prephenate in the biosynthesis of the aromatic amino acids tyrosine and phenylalanine in bacteria, fungi and plants. Here, the crystallization of the unusual secreted chorismate mutase from Mycobacterium tuberculosis (encoded by Rv1885c), a 37.2 kDa dimeric protein belonging to the AroQ(gamma) subclass of mutases, is reported. Crystal optimization was non-trivial and is discussed in detail. To obtain crystals of sufficient quality, it was critical to initiate crystallization at higher precipitant concentration and then transfer the drops to lower precipitant concentrations within 5-15 min, in an adaptation of a previously described technique [Saridakis & Chayen (2000), Protein Sci. 9, 755-757]. As a result of the optimization, diffraction improved from 3.5 to 1.3 A resolution. The crystals belong to space group P2(1), with unit-cell parameters a = 42.6, b = 72.6, c = 62.0 angstroms, beta = 104.5 degrees. The asymmetric unit contains one biological dimer, with 167 amino acids per protomer. A soak with a transition-state analogue is also described.
authors: Department of Chemistry and Bioscience, Chalmers University of Technology, PO Box 462, SE-40530 Göteborg, Sweden. ute.krengel@kjemi.uio.no
authors: Ute
authors: U
authors: Krengel
authors: Raja
authors: R
authors: Dey
authors: Severin
authors: S
authors: Sasso
authors: Mats
authors: M
authors: Okvist
authors: Chandra
authors: C
authors: Ramakrishnan
authors: Peter
authors: P
authors: Kast