Avtor/Urednik		Knecht, W; Petersen, GE; Munch-Petersen, B; Piškur, J
Naslov		Deoxyribonucleoside kinases belonging to the thymidine kinase 2 (TK2)-like group vary significantly in substrate specificity, kinetics and feed-back regulation
Tip		članek
Vir		J Mol Biol
Vol. in št.		Letnik 315, št. 4
Leto izdaje		2002
Obseg		str. 529-40
Jezik		eng
Abstrakt		In eukaryotic cells deoxyribonucleoside kinases belonging to three phylogenetic sub-families have been found: (i) thymidine kinase 1 (TK1)-like enzymes, which are strictly pyrimidine deoxyribonucleoside-specific kinases; (ii) TK2-like enzymes, which include pyrimidine deoxyribonucleoside kinases and a single multisubstrate kinase from Drosophila melanogaster (Dm-dNK); and (iii) deoxycytidine/deoxyguanosine kinase (dCK/dGK)-like enzymes, which are deoxycytidine and/or purine deoxyribonucleoside-specific kinases. We cloned and characterized two new deoxyribonucleoside kinases belonging to the TK2-like group from the insect Bombyx mori and the amphibian Xenopus laevis. The deoxyribonucleoside kinase from B. mori (Bm-dNK) turned out to be a multisubstrate kinase like Dm-dNK. But uniquely for a deoxyribonucleoside kinase, Bm-dNK displayed positive cooperativity with all four natural deoxyribonucleoside substrates. The deoxyribonucleoside kinase from X. laevis (Xen-PyK) resembled closely the human and mouse TK2 enzymes displaying their characteristic Michaelis-Menten kinetic with deoxycytidine and negative cooperativity with its second natural substrate thymidine. Bm-dNK, Dm-dNK and Xen-PyK were shown to be homodimers. Significant differences in the feedback inhibition by deoxyribonucleoside triphosphates between these three enzymes were found. The insect multisubstrate deoxyribonucleoside kinases Bm-dNK and Dm-dNK were only inhibited by thymidine triphosphate, while Xen-PyK was inhibited by thymidine and deoxycytidine triphosphate in a complex pattern depending on the deoxyribonucleoside substrate. The broad substrate specificity and different feedback regulation of the multisubstrate insect deoxyribonucleoside kinases may indicate that these enzymes have a different functional role than the other members of the TK2-like group.
Deskriptorji		CHEMISTRY GENETICS METABOLISM AMINO ACID SEQUENCE ANIMALS CHICKENS CHROMATOGRAPHY, GEL DEOXYCYTIDINE DROSOPHILA MELANOGASTER KINETICS MICE MODELS, BIOLOGICAL MODELS, MOLECULAR MOLECULAR SEQUENCE DATA PHOSPHOTRANSFERASES (ALCOHOL GROUP ACCEPTOR) PHYLOGENY RECOMBINANT FUSION PROTEINS SEQUENCE ALIGNMENT SEQUENCE DELETION SUBSTRATE SPECIFICITY THYMIDINE KINASE XENOPUS LAEVIS