Author/Editor		Knecht, Wolfgang; Sandrini, Michael PB; Johansson, Kenth; Eklund, Hans; Munch-Petersen, Birgitte; Piškur, Jure
Title		A few amino acid substitutions can convert deoxyribonucleoside kinase specificity from pyrimidines to purines
Type		članek
Source		EMBO J
Vol. and No.		Letnik 21, št. 7
Publication year		2002
Volume		str. 1873-80
Language		eng
Abstract		In mammals, the four native deoxyribonucleosides are phosphorylated to the corresponding monophosphates by four deoxyribonucleoside kinases, which have specialized substrate specificities. These four enzymes are likely to originate from a common progenitor kinase. Insects appear to have only one multisubstrate deoxyribonucleoside kinase (dNK, EC 2.7.1.145), which prefers pyrimidine nucleosides, but can also phosphorylate purine substrates. When the structures of the human deoxyguanosine kinase (dGK, EC 2.7.1.113) and the dNK from Drosophila melanogaster were compared, a limited number of amino acid residues were identified and proposed to be responsible for the substrate specificity. Three of these key residues in Drosophila dNK were then mutagenized and the mutant enzymes were characterized regarding their ability to phosphorylate native deoxyribonucleosides and nucleoside analogs. The mutations converted the dNK substrate specificity from predominantly pyrimidine specific into purine specific. A similar scenario could have been followed during the evolution of kinases. Upon gene duplication of the progenitor kinase, only a limited number of single amino acid changes has taken place in each copy and resulted in substrate-specialized enzymes.
Descriptors		AMINO ACID SEQUENCE ANIMALS DEOXYRIBONUCLEOSIDES MICE MOLECULAR SEQUENCE DATA MUTAGENESIS, SITE-DIRECTED PHOSPHORYLATION PHOSPHOTRANSFERASES (ALCOHOL GROUP ACCEPTOR) PURINES PYRIMIDINES SEQUENCE HOMOLOGY, AMINO ACID SUBSTRATE SPECIFICITY