Cloning, sequence analysis and overexpression of a Rhodothermus marinus gene encoding a thermostable thymidine kinase

Thymidine kinase type II is an important part of the pyrimidine salvage pat hway. The thymidine kinase gene from the thermophilic eubacterium Rhodother mus marinus was cloned, sequenced and overexpressed. The gene is 639 bp and encodes a protein of 213 amino acids with a calculated molecular mass of 2 3.6 kDa, It shows homology to other thymidine kinase proteins from eukaryot ic and prokaryotic organisms, The recombinant protein is inhibited by dNTPs but not by dNDPs. It is a tetramer in its native slate. Its optimum temper ature of activity is 65 degrees C and it has a half life of 15 min at 90 de grees C. This is the first thymidine kinase to be described from a thermoph ilic bacterium. (C) 1999 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.