Incorporation of selected nucleoside phosphonates and anti-human immunodeficiency virus nucleotide analogues into DNA by human DNA polymerases alpha, beta and gamma

Incorporation of selected diphosphates of nucleoside phosphonates and triphosphates of currently approved anti-human immunodeficiency virus nucleoside analogues into DNA by human DNA polymerases alpha, beta and gamma was studied. All three polymerases were able to incorporate diphosphates of 9-(2-phosphonomethoxyethyl)adenine (PMEApp), 9-(2-phosphonomethoxyethyl)guanine (PMEGpp), (R)-9-(2-phosphonomethoxypropyl)adenine (PMPApp), (R)-9-(2-phosphononomethoxypropyl)-2,6-diaminopurine (PMPDAPpp) and (2R,5R)-9-[2,5-dihydro-5-(phosphonomethoxy)-2-furanyl]adenine (D4APpp) into primer/template DNA of defined sequence. After incorporation, these nucleoside phosphonates acted as terminators of primer extension. Kinetic constants of their incorporation were determined and compared with those for incorporation of ddATP, ddCTP, (-)-2'-deoxy-3'-thiacytidine triphosphate (3TC-TP), 2',3'-didehydro-3'-deoxythymidine triphosphate (d4T-TP) and 3'-azido-3'-deoxythymidine triphosphate (AZT-TP). Relative efficiencies of incorporation (percentage of the incorporation efficiency for the corresponding natural deoxynucleoside triphosphate) by DNA polymerase alpha ranged from 0.05% for 3TC-TP to 51% for PMEGpp. DNA polymerase beta catalysed the incorporation with relative efficiencies ranging from 0.014% for AZT-TP to 125% for ddCTP, and efficiencies of incorporation by DNA polymerase gamma varied between 0.13% for 3TC-TP and 25% for ddCTP. Generally, the lowest incorporation efficiencies with all three polymerases were found for PMPApp (0.06-1.4%) and PMPDAPpp (0.075-2.2%).