HERPESVIRAL DEOXYTHYMIDINE KINASES CONTAIN A SITE ANALOGOUS TO THE PHOSPHORYL-BINDING ARGININE-RICH REGION OF PORCINE ADENYLATE KINASE - COMPARISON OF SECONDARY STRUCTURE PREDICTIONS AND CONSERVATION

Twelve herpesviral deoxythymidine kinases were examined for regions of sequence similarity by multiple alignment. Six highly conserved sites were observed. Site 1 corresponded to a glycine-rich loop that forms part of the ATP-binding pocket in porcine adenylate kinase (PAK), and site 5 corresponded to a region in PAK, located on one lobe of the cleft, that contains arginine residues that bind substrate phosphoryl groups. Site 3, consisting of the motif -DRH-, is thought to be involved in thymine/deoxythymidine recognition; site 4, which is nearby, probably participates in this function as well. The functions of sites 2 and 6 have not been identified. Secondary structure predictions were made by the Garnier method and averaged for each position in the multiple alignment. The structure predicted for all six sites was typically a short flexible region (turn or coil) at or adjacent to the site, flanked by rigid structures (helix or sheet) on either side.