Structural-Functional Relationships between Terminal Deoxynucleotidyltransferase and 5´-Triphosphates of Nucleoside Analogs

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M. K. Kukhanova^1*, A. V. Ivanov^1,2, and M. V. Jasko¹

¹Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, ul. Vavilova 32, 119991 Moscow, Russia; fax: (7-095) 135-1405; E-mail: kukhan86@hotmail.com

²Center for Medical Studies, University of Oslo, ul. Vavilova 34/5, 119991 Moscow, Russia

^* To whom correspondence should be addressed.

Received June 24, 2004; Revision received August 26, 2004

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Substrate properties of nucleoside 5´-triphosphate (NTP) analogs, namely, 5´-triphosphates of L- and D-arabinonucleosides (D-FIAUTP, D-FMAUTP, and L-FMAUTP), D- and L-enantiomers of ddCTP analogs (D-ddCTP, L-ddCTP, D-FOddCTP, L-OddCTP, and L-SddCTP), and acyclic guanosine analogs (acyclovir and penciclovir) towards terminal deoxynucleotidyltransferase (TdT, EC 2.7.7.31) were studied. TdT can polymerize 5´-triphosphates of arabinonucleoside analogs (D-FIAUTP and D-FMAUTP). In contrast, L-FMAUTP is not recognized by TdT as a substrate. Kinetic parameters of D- and L-enantiomers of ddCTP analogs and 5´-triphosphates of acyclic nucleosides were evaluated. It is shown that stereospecificity of dNTP analogs and structure of the furanose residue play crucial roles in the interaction with TdT: L-enantiomers are much less potent as substrates compared to their D-counterparts. 5´-Triphosphates of acyclovir (ACVTP) and penciclovir (PCVTP) are about two orders of magnitude less effective as substrates than nucleosides bearing furanose residues, with PCVTP being a better substrate than ACVTP. It can be assumed that the hydroxyl group of PCVTP mimics the 3´-hydroxyl group of the ribose residue and plays an important role in the interaction with TdT.

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KEY WORDS: nucleoside 5´-triphosphate analogs, terminal deoxynucleotidyltransferase, kinetic parameters

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