title: Expression, purification, crystallization and preliminary X-ray diffraction analysis of the transcriptional repressor SirR from Mycobacterium tuberculosis H37Rv.
abstract: SirR, a metal-dependent transcriptional repressor from Mycobacterium tuberculosis (Rv2788), was cloned in pQE30 expression vector with an N-terminal His(6) tag for heterologous overexpression in Escherichia coli M15 (pREP4) cells and purified to homogeneity using chromatographic procedures. The purified protein was crystallized using the sitting-drop vapour-diffusion technique. The crystals belonged to the tetragonal space group P4(1)2(1)2/P4(3)2(1)2, with unit-cell parameters a = 105.21, b = 105.21, c = 144.85 A. The X-ray diffraction data were processed to a maximum resolution of 2.5 A. The Matthews coefficient suggests the presence of two (V(M) = 4.01 A(3) Da(-1)) to four (V(M) = 2.0 A(3) Da(-1)) molecules in the asymmetric unit. Calculation of the self-rotation function shows a crystallographic fourfold symmetry axis along the z axis (chi = 90 degrees) and also a twofold symmetry axis around the z axis (chi = 180 degrees).
authors.affiliation: Department of Biotechnology, Indian Institute of Technology, Kharagpur 721 302, India.
authors.forename: Baisakhee
authors.initials: B
authors.lastname: Saha
authors.forename: Somnath
authors.initials: S
authors.lastname: Mukherjee
authors.forename: Debajyoti
authors.initials: D
authors.lastname: Dutta
authors.forename: Amit Kumar
authors.initials: AK
authors.lastname: Das
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D003460:Crystallization; D018360:Crystallography, X-Ray; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology; D008969:Molecular Sequence Data; D009169:Mycobacterium tuberculosis; D012097:Repressor Proteins / Q000096:biosynthesis / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification
chemical_list: D001426:Bacterial Proteins; D012097:Repressor Proteins