Kim G J, Park J H, Lee D C, Ro H S, Kim H S
Department of Biological Sciences, Korea Advanced Institute of Sciences and Technology, Kusong-dong Yusong-gu, Taejon, Korea.
Mol Gen Genet. 1997 Jun;255(2):152-6. doi: 10.1007/pl00008610.
The gene coding for the thermostable D-hydantoinase from the thermophilic bacterium Bacillus stearothermophilus SD1 was cloned and its nucleotide sequence was completely determined. The D-hydantoinase protein showed considerable amino acid sequence homology (20-28%) with other hydantoinases and functionally related allantoinases and dihydroorotases. Strikingly the sequence of the enzyme from B. stearothermophilus SD1 exhibited greater than 89% identity with hydantoinases from thermophilic bacteria. Despite the extremely high amino acid homology among the hydantoinases from thermophiles, the C-terminal regions of the enzymes were completely different in both sequence and predicted secondary structure, implying that the C-terminal region plays an important role in determining the biochemical properties of the enzymes. Alignment of the sequence of the D-hydantoinase from B. stearothermophilus SD1 with those of other functionally related enzymes revealed four conserved regions, and five histidines and an acidic residue were found to be conserved, suggesting a close evolutionary relationship between all these enzymes.
