title: Crystallization and preliminary crystallographic analysis of D-alanine-D-alanine ligase from Streptococcus mutans.
abstract: D-Alanine-D-alanine ligase is encoded by the gene ddl (SMU_599) in Streptococcus mutans. This ligase plays a very important role in cell-wall biosynthesis and may be a potential target for drug design. To study the structure and function of this ligase, the gene ddl was amplified from S. mutans genomic DNA and cloned into the expression vector pET28a. The protein was expressed in soluble form in Escherichia coli strain BL21 (DE3). Homogeneous protein was obtained using a two-step procedure consisting of Ni2+-chelating and size-exclusion chromatography. Purified protein was crystallized and the cube-shaped crystal diffracted to 2.4 A. The crystal belongs to space group P3(1)21 or P3(2)21, with unit-cell parameters a = b = 79.50, c = 108.97 A. There is one molecule per asymmetric unit.
authors.affiliation: Institute for Nanobiomedical Technology and Membrane Biology, West China Hospital, Sichuan University, Chengdu 610065, Sichuan, People's Republic of China.
authors.forename: Yong-Zhi
authors.initials: YZ
authors.lastname: Lu
authors.forename: Yu
authors.initials: Y
authors.lastname: Sheng
authors.forename: Lan-Fen
authors.initials: LF
authors.lastname: Li
authors.forename: De-Wei
authors.initials: DW
authors.lastname: Tang
authors.forename: Xiang-Yu
authors.initials: XY
authors.lastname: Liu
authors.forename: Xiaojun
authors.initials: X
authors.lastname: Zhao
authors.forename: Yu-He
authors.initials: YH
authors.lastname: Liang
authors.forename: Xiao-Dong
authors.initials: XD
authors.lastname: Su
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000302:isolation & purification; D003001:Cloning, Molecular; D003460:Crystallization; D018360:Crystallography, X-Ray; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry; D010453:Peptide Synthases / Q000737:chemistry* / Q000302:isolation & purification; D011994:Recombinant Proteins / Q000737:chemistry / Q000302:isolation & purification; D013295:Streptococcus mutans / Q000201:enzymology*
chemical_list: D001426:Bacterial Proteins; D010446:Peptide Fragments; D011994:Recombinant Proteins; D010453:Peptide Synthases; C019638:D-alanylalanine synthetase