title: Crystallization and preliminary X-ray studies of Trp138Phe/Val185Thr xylose isomerases from Thermotoga neapolitana and Thermoanaerobacterium thermosulfurigenes.
abstract: Xylose isomerases from Thermotoga neapolitana (TNXI) and Thermoanaerobacterium thermosulfurigenes (TTXI) share 70.4% sequence identity and are thermostable. The double mutants Trp138Phe/Val185Thr of TNXI and TTXI have higher catalytic efficiencies than TNXI and TTXI, respectively. The Trp138Phe/Val185Thr TNXI and TTXI mutants were overexpressed in Escherichia coli strain BL21(DE3) and purified. Crystals of the two proteins were grown with polyethylene glycol 8000 as the major precipitant by the hanging-drop vapour-diffusion method. Crystals of the TNXI mutant were obtained in the absence of substrate, in complex with glucose and in complex with fructose. Crystals of the TTXI mutant were obtained complexed with glucose. Diffraction data were collected at 1.9, 2.1 and 2.1 A resolution for the fructose-TNXI mutant, glucose-TNXI mutant and substrate-unbound TNXI mutant, respectively. The diffraction data for the glucose-TTXI mutant were collected at 2.0 A resolution. The crystals belong to the orthorhombic space groups C222(1) (TNXI mutant) and P2(1)2(1)2(1) (TTXI mutant). The TNXI and TTXI mutant crystals contain two and four monomers in the asymmetric unit, respectively.
authors.affiliation: Department of Life Science, Kwangju Institute of Science and Technology, Kwangju 500-712, South Korea.
authors.forename: Y S
authors.initials: YS
authors.lastname: Kim
authors.forename: Y J
authors.initials: YJ
authors.lastname: Im
authors.forename: S H
authors.initials: SH
authors.lastname: Rho
authors.forename: D
authors.initials: D
authors.lastname: Sriprapundh
authors.forename: C
authors.initials: C
authors.lastname: Vieille
authors.forename: S W
authors.initials: SW
authors.lastname: Suh
authors.forename: J G
authors.initials: JG
authors.lastname: Zeikus
authors.forename: S H
authors.initials: SH
authors.lastname: Eom
mesh_terms: D019747:Aldose-Ketose Isomerases / Q000737:chemistry* / Q000235:genetics; D019943:Amino Acid Substitution; D001407:Bacillus / Q000201:enzymology*; D003460:Crystallization; D018360:Crystallography, X-Ray; D006088:Gram-Negative Aerobic Bacteria / Q000201:enzymology*; D010649:Phenylalanine / Q000235:genetics; D011487:Protein Conformation; D013912:Threonine / Q000235:genetics; D014364:Tryptophan / Q000235:genetics; D014633:Valine / Q000235:genetics
chemical_list: D013912:Threonine; D010649:Phenylalanine; D014364:Tryptophan; D019747:Aldose-Ketose Isomerases; C023298:xylose isomerase; D014633:Valine