Using Pyrrolo-deoxycytosine to Probe RNA/DNA Hybrids Containing the Human Immunodeficiency Virus Type-1 3' Polypurine Tract
Overview
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Recent structural analyses indicate that localized regions of abnormal base pairing exist within RNA/DNA hybrids containing the HIV-1 polypurine tract (PPT) and that these distortions may play a role in PPT function. To examine this directly, we have introduced pyrrolo-deoxycytosine (pdC), a fluorescent, environmentally sensitive analog of deoxycytosine (dC), into the DNA strand of PPT-containing hybrids. Steady-state fluorescence analysis of these hybrids reveals that the DNA base 11 nt from the PPT-U3 junction is unpaired even in the absence of reverse transcriptase (RT). Unstable base pairing is also observed within the (rG:dC)6 tract in the downstream portion of the duplex, suggesting that HIV-1 RT may recognize multiple pre-existing distortions during PPT selection. HIV-1 RT hydrolyzes pdC-containing hybrids primarily at the PPT-U3 junction, indicating that the analog does not induce a gross structural deformation of the duplex. However, aberrant cleavage is frequently observed 3 bp from the site of pdC substitution, most likely reflecting a specific interaction between the analog and amino acid residues within the RNase H primer grip. pdC substitution within the template strand of a DNA duplex does not appear to significantly affect RT-catalyzed DNA synthesis. Implications of these findings on the use of pdC to examine nucleic acid structure are discussed.
Chowdhury M, John A, Hudson R RSC Adv. 2024; 14(50):37605-37609.
PMID: 39588240 PMC: 11586925. DOI: 10.1039/d4ra07000c.
Konttinen O, Carmody J, Kurnik M, Johnson K, Reich N Nucleic Acids Res. 2023; 51(13):6883-6898.
PMID: 37326016 PMC: 10359602. DOI: 10.1093/nar/gkad443.
Kotandeniya D, Rogers M, Fernandez J, Kanugula S, Hudson R, Rodriguez F Biopolymers. 2020; 112(1):e23405.
PMID: 33098572 PMC: 7856187. DOI: 10.1002/bip.23405.
Konttinen O, Carmody J, Pathuri S, Anderson K, Zhou X, Reich N Nucleic Acids Res. 2020; 48(20):11589-11601.
PMID: 33053173 PMC: 7672430. DOI: 10.1093/nar/gkaa844.
Mechanism of polypurine tract primer generation by HIV-1 reverse transcriptase.
Figiel M, Krepl M, Park S, Poznanski J, Skowronek K, Golab A J Biol Chem. 2017; 293(1):191-202.
PMID: 29122886 PMC: 5766924. DOI: 10.1074/jbc.M117.798256.