Crystallization and X-ray crystallographic studies of wild-type and mutant tryptophan synthase alpha-subunits from Escherichia coli.
The alpha-subunit of Escherichia coli tryptophan synthase (aTS), a component of the tryptophan synthase alpha2beta2 complex, is a monomeric 268-residues protein (Mr = 28,600). alphaTS by itself catalyzes the cleavage of indole-3-glycerol phosphate to glyceraldehyde-3-phosphate and indole, which is converted to tryptophan in tryptophan biosynthesis. Wild-type and P28L/Y173F double mutant alpha-subunits were overexpressed in E. coli and crystallized at 298 K by the hanging-drop vapor-diffusion method. X-ray diffraction data were collected to 2.5 angstroms resolution from the wild-type crystals and to 1.8 angstroms from the crystals of the double mutant, since the latter produced better quality diffraction data. The wild-type crystals belonged to the monoclinic space group C2 (a = 155.64 angstroms, b = 44.54 angstroms, c = 71.53 angstroms and beta = 96.39 degrees) and the P28L/Y173F crystals to the monoclinic space group P21 (a = 71.09 angstroms, b = 52.70, c = 71.52 angstroms, and beta = 91.49 degrees). The asymmetric unit of both structures contained two molecules of aTS. Crystal volume per protein mass (V(m)) and solvent content were 2.15 angstroms3 Da(-1) and 42.95% for the wild-type and 2.34 angstroms3 Da(-1) and 47.52% for the double mutant.
Jeong
Mi Suk
MS
Korea Nanobiotechnology Center, Pusan National University, Busan 609-735, Korea.
Jang
Se Bok
SB
D000595:Amino Acid Sequence; D003460:Crystallization; D018360:Crystallography, X-Ray; D004926:Escherichia coli / Q000201:enzymology*; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics*; D021122:Protein Subunits; D017386:Sequence Homology, Amino Acid; D014367:Tryptophan Synthase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
D021122:Protein Subunits; D014367:Tryptophan Synthase