title: Crystallization and preliminary X-ray crystallographic analysis of SMU.412c protein from the caries pathogen Streptococcus mutans.
abstract: The smu.412c gene encodes a putative histidine triad-like protein (SMU.412c) with 139 residues that is involved in cell-cycle regulation in Streptococcus mutans. The gene was cloned into the expression vector pET28a and subsequently expressed in Escherichia coli strain BL21 (DE3) to give a substantially soluble form of SMU.412c with a His(6) tag at its N-terminus. The recombinant protein was purified to homogeneity in a two-step procedure involving Ni(2+)-chelating and size-exclusion chromatography. Crystals suitable for X-ray diffraction were obtained using the sitting-drop vapour-diffusion method and diffracted to 1.8 A resolution on beamline BL6A at Photon Factory, Tsukuba, Japan. The crystal belonged to space group P4(1)2(1)2, with unit-cell parameters a = b = 53.5, c = 141.1 A.
authors.affiliation: Peking University Shenzhen Graduate School, Shenzhen 518055, People's Republic of China.
authors.forename: Zhao Yang
authors.initials: ZY
authors.lastname: Ye
authors.forename: Qiao Ming
authors.initials: QM
authors.lastname: Hou
authors.forename: Lan Fen
authors.initials: LF
authors.lastname: Li
authors.forename: Xiao Dong
authors.initials: XD
authors.lastname: Su