The structural consequences of exchanging tryptophan and tyrosine residues in B. stearothermophilus lactate dehydrogenase.
A mutant Bacillus stearothermophilus lactate dehydrogenase has been prepared in which all three tryptophan residues in the wild-type enzyme have been replaced by tyrosines. In addition, a tyrosine residue has been mutated to a tryptophan, which acts as a fluorescence probe to monitor protein folding. The mutant enzyme crystallizes in the same crystal form as the wild-type. The crystal structure of the mutant has been determined at 2.8 A resolution. Solution studies have suggested that there is little effect upon the mutant enzyme as judged by its kinetic properties. Comparison of the crystal structures of the mutant and wild-type enzymes confirms this conclusion, and reveals that alterations in structure in the region of these mutations are of a similar magnitude to those observed throughout the structure, and are not significant when compared with the errors in atomic positions expected for a structure at this resolution.
Roper
D I
DI
Department of Chemistry, University of York, Heslington, UK.
Moreton
K M
KM
Wigley
D B
DB
Holbrook
J J
JJ
D005818:Genetic Engineering; D001411:Geobacillus stearothermophilus / Q000201:enzymology*; D007770:L-Lactate Dehydrogenase / Q000737:chemistry* / Q000235:genetics; D008958:Models, Molecular; D011487:Protein Conformation; D014364:Tryptophan; D014443:Tyrosine; D014961:X-Ray Diffraction
D014443:Tyrosine; D014364:Tryptophan; D007770:L-Lactate Dehydrogenase