NDP kinase reactivity towards 3TC nucleotides

Area of Science:

• Biochemistry
• Enzymology
• Antiviral Drug Development

Background:

• Nucleoside diphosphate (NDP) kinase is crucial for synthesizing active antiviral nucleoside analogs.
• Current understanding assumes NDP kinase efficiently phosphorylates various nucleoside analogs for AIDS therapy.
• Lamivudine (3TC), an L-configuration nucleoside analog, is widely used in AIDS treatment.

Purpose of the Study:

• To investigate the reactivity of L-configuration nucleoside analogs, specifically lamivudine triphosphate, with NDP kinase.
• To compare the phosphorylation efficiency of L-dideoxynucleotides versus their D-enantiomers by NDP kinase.
• To re-evaluate the role of NDP kinase in the phosphorylation of lamivudine diphosphate.

Main Methods:

• Utilized protein fluorescence to monitor enzyme-substrate interactions during phosphotransfer.
• Studied presteady-state kinetics of NDP kinase with L-dideoxynucleotides.
• Employed computer modeling to analyze the binding of 3TC diphosphate in the NDP kinase active site.

Main Results:

• L-dideoxynucleoside triphosphates exhibit poor affinity for NDP kinase.
• The catalytic efficiency for phosphorylating L-dideoxyderivatives is significantly lower than for their D-enantiomers.
• NDP kinase may not be the primary enzyme responsible for phosphorylating lamivudine diphosphate.

Conclusions:

• NDP kinase's role in phosphorylating L-configuration nucleoside analogs like lamivudine is less significant than previously thought.
• The poor affinity and low catalytic efficiency suggest alternative enzymes are likely involved in lamivudine activation.
• Findings necessitate a re-evaluation of cellular phosphorylation pathways for L-enantiomer antiviral drugs.