Cloning, nucleotide sequence and expression of a hydantoinase and carbamoylase gene from Arthrobacter aurescens DSM 3745 in Escherichia coli and comparison with the corresponding genes from Arthrobacter aurescens DSM 3747

The genes encoding hydantoinases (hyuH1) and carbamoylases (hyuC1) from Arthrobacter aurescens DSM 3745 and Arthrobacter aurescens DSM 3747 (hyuH2, hyuC2) were cloned in Escherichia coli and the nucleotide sequences determined. The hydantoinase genes comprised 1,377 base pairs and the carbamoylase genes 1,239 base pairs each. Both hydantoinases, as well as both carbamoylases, showed a high degree of nucleotide and amino acid sequence identity (96-98%). The hyuH and hyuC genes were expressed in E. coli under the control of the rhamnose promoter and the different specific activities obtained in E. coli crude extracts were compared to those produced by the original hosts. For purification the hyuH2 gene was expressed as a maltose-binding protein (MalE) and as an intein-chitin binding domain (CBD) fusion in E. coli. The expression of malE-hyuH2 resulted in the production of more soluble and active protein. With respect to temperature stability, optimal pH and optimal temperature, substrate and stereospecificity, the purified fusion enzyme exhibited properties similar to those of the wild-type enzyme.