To identify enzymes of T. maritima involved in the phosphorylation of nucleosides we analyzed both the KEGG database and the T. maritima genome (Figure , Figure ). Next to the known TmTK , in the genome an adenosine-specific kinase (TmAsK) and a three-domain uridine kinase (TmUK, annotated as nucleoside kinase in the genome sequence) were found. Adenosinespecific kinases are rarely studied and the TmUK shows an unusual protein sequence as it consists of a nucleoside kinase superfamily domain and a threonyl-tRNA synthetase domain (Figure ). Neither a deoxycytidine kinase (dCK), a (deoxy)adenosine ((d)AK), an inosine kinase (IK), deoxyguanosine (dGK) nor a deoxynucleoside kinase was found in T. maritima (Figure , Figure ).