Mechanism by Which Phosphonoformic Acid Resistance Mutations Restore 3′-Azido-3′-deoxythymidine (AZT) Sensitivity to AZT-resistant HIV-1 Reverse Transcriptase

Arion, Dominique; Sluis‐Cremer, Nicolas; Parniak, Michael A.

doi:10.1074/jbc.275.13.9251

Cited by 55 publications

(57 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The NRTI-MP excision activities of WT, K65R, and K70E HIV-1 RT were investigated by measuring the abilities of WT or mutant RT to excise AZT-MP, 3TC-MP, CBV-MP, or TNV from the 3Ј terminus of the primer and to rescue DNA synthesis, as described previously (2). Excision assays were carried out using either ATP or pyrophosphate as the phosphate donor ( Fig.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Molecular Mechanism by Which the K70E Mutation in Human Immunodeficiency Virus Type 1 Reverse Transcriptase Confers Resistance to Nucleoside Reverse Transcriptase Inhibitors

Sluis‐Cremer

Sheen

Zelina

et al. 2007

Antimicrob Agents Chemother

Self Cite

View full text Add to dashboard Cite

The K70E mutation in human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) has become more prevalent in clinical samples, particularly in isolates derived from patients for whom triple-nucleoside regimens that include tenofovir (TNV), abacavir, and lamivudine (3TC) failed. To elucidate the molecular mechanism by which this mutation confers resistance to these nucleoside RT inhibitors (NRTI), we conducted detailed biochemical analyses comparing wild-type (WT), K70E, and K65R HIV-1 RT. Pre-steady-state kinetic experiments demonstrate that the K70E mutation in HIV-1 RT allows the enzyme to discriminate between the natural deoxynucleoside triphosphate substrate and the NRTI triphosphate (NRTI-TP). Compared to the WT enzyme, K70E RT showed 2.1-, 2.3-, and 3.5-foldhigher levels of resistance toward TNV-diphosphate, carbovir-TP, and 3TC-TP, respectively. By comparison, K65R RT demonstrated 12.4-, 12.0-, and 13.1-fold-higher levels of resistance, respectively, toward the same analogs. NRTI-TP discrimination by the K70E (and K65R) mutation was primarily due to decreased rates of NRTI-TP incorporation and not to changes in analog binding affinity. The K65R and K70E mutations also profoundly impaired the ability of RT to excise 3 -azido-2 ,3 -dideoxythymidine monophosphate (AZT-MP) and other NRTI-MP from the 3 end of a chain-terminated primer. When introduced into an enzyme with the thymidine analog mutations (TAMs) M41L, L210W, and T215Y, the K70E mutation inhibited ATP-mediated excision of AZT-MP. Taken together, these findings indicate that the K70E mutation, like the K65R mutation, reduces susceptibility to NRTI by selectively decreasing NRTI-TP incorporation and is antagonistic to TAM-mediated nucleotide excision.

show abstract

Section: Resultsmentioning

confidence: 99%

“…For 3TC-MP excision assays, 1 M dCTP, 1 M TTP, and 5 M ddATP were included in the reaction mixture. After defined incubation periods, aliquots were removed and processed as described previously (2).…”

Section: Methodsmentioning

confidence: 99%

Molecular Mechanism by Which the K70E Mutation in Human Immunodeficiency Virus Type 1 Reverse Transcriptase Confers Resistance to Nucleoside Reverse Transcriptase Inhibitors

Sluis‐Cremer

Sheen

Zelina

et al. 2007

Antimicrob Agents Chemother

Self Cite

View full text Add to dashboard Cite

show abstract

“…W88G, E89K, A114S, S117T, Q161L, and M164I) (56,57) and with the deletion of Thr 69 , which is often associated with the Q151M complex (58 -60). All of those mutations increase HIV-1 susceptibility to AZT by reducing the phosphorolytic activity of the enzyme.…”

Section: Discussionmentioning

confidence: 99%

Thymidine Analogue Resistance Suppression by V75I of HIV-1 Reverse Transcriptase

Matamoros

Nevot

Martı́nez

et al. 2009

Journal of Biological Chemistry

View full text Add to dashboard Cite

Val75 of HIV-1 reverse transcriptase (RT) plays a role in positioning the template nucleotide ؉1 during the formation of the ternary complex. Mutations, such as V75M and V75A, emerge in patients infected with HIV-1 group M subtype B and group O variants, after failing treatment with stavudine (d4T) and other nucleoside RT inhibitors. V75I is an accessory mutation of the Q151M multidrug resistance complex of HIV-1 RT and is rarely associated with thymidine analogue resistance mutations (TAMs). In vitro, it confers resistance to acyclovir. TAMs confer resistance to zidovudine (AZT) and d4T by increasing the rate of ATP-mediated excision of the terminal nucleotide monophosphate (primer unblocking). In a wild-type HIV-1 group O RT sequence context, V75A and V75M conferred increased excision activity on d4T-terminated primers, in the presence of PP i . In contrast, V75I decreased the PP i -mediated unblocking efficiency on AZT and d4T-terminated primers, in different sequence contexts (i.e. wild-type group M subtype B or group O RTs). Interestingly, in the sequence context of an excision-proficient RT (i.e. M41L/A62V/T69SSS/K70R/ T215Y), the introduction of V75I led to a significant decrease of its ATP-dependent excision activity on AZT-, d4T-, and acyclovir-terminated primers. The excision rate of d4T-monophosphate in the presence of ATP (3.2 mM) was about 10 times higher for M41L/A62V/T69SSS/K70R/T215Y than for the mutant M41L/A62V/T69SSS/K70R/V75I/T215Y RT. The antagonistic effect of V75I with TAMs was further demonstrated in phenotypic assays. Recombinant HIV-1 containing the M41L/A62V/ T69SSS/K70R/V75I/T215Y RT showed 18.3-and 1.5-fold increased susceptibility to AZT and d4T, respectively, in comparison with virus containing the M41L/A62V/T69SSS/K70R/ T215Y RT.

show abstract

“…Most importantly, mutations associated with PFA resistance were shown to increase susceptibility to the nucleoside analogue 3Ј-azido-3Ј-deoxythymidine (zidovudine or AZT) (10, 11). Biochemical data have shown that PFA-associated resistance mutations diminish the phosphorolytic excision of incorporated chain terminators such as 12). Wild type HIV-1 RT is capable of removing AZT-monophosphate in the presence of pyrophosphate (PP i ) (13), or a PP i donor such as ATP (14).…”

mentioning

confidence: 99%

The Pyrophosphate Analogue Foscarnet Traps the Pre-translocational State of HIV-1 Reverse Transcriptase in a Brownian Ratchet Model of Polymerase Translocation

Marchand

Tchesnokov

Götte

2007

Journal of Biological Chemistry

View full text Add to dashboard Cite

The pyrophosphate (PPi) analogue phosphonoformic acid (PFA or foscarnet) inhibits the reverse transcriptase (RT) of the human immunodeficiency virus type 1 (HIV-1); however, the mechanisms of drug action and resistance remain elusive. Here we studied the effects of the translocational status of HIV-1 RT on drug binding and inhibition of DNA synthesis. We identified "hot spots" for inhibition during active elongation. Site-specific footprinting analyses revealed that the corresponding complexes exist predominantly in the pre-translocational state. The sensitivity to PFA is significantly reduced with sequences that show a bias toward the post-translocational state. Binding studies showed that PFA stabilizes selectively the complex in the pre-translocated configuration. These findings are consistent with a Brownian ratchet model of polymerase translocation. The enzyme can rapidly shuttle between pre-and post-translocated states. The bound inhibitor acts like a pawl of a ratchet and prevents the forward motion of HIV-1 RT, whereas the bound nucleotide binds to the post-translocated complex and prevents the reverse motion. The proposed mechanisms of RT translocation and drug action are consistent with the PFA-resistant phenotypes. We show that certain sequences and the PFA-resistant E89K mutant diminishes the stability of the pre-translocated complex. In these cases, the enzyme is seen at multiple positions around the 3 end of the primer, which provides a novel mechanism for resistance. These findings validate the pre-translocated complex as a target for the development of novel, perhaps less toxic and more potent inhibitors that block HIV-1 RT translocation.Different classes of inhibitors that target the reverse transcriptase (RT) 4 of the human immunodeficiency virus type 1 (HIV-1) have been developed (1). Nucleoside analogue reverse transcriptase inhibitors (NRTIs) are major components in drug regimens that are currently used in the clinic. Two different NRTIs are usually combined with a non-nucleoside analogue RT inhibitor (NNRTI) or a protease inhibitor. The triphosphate forms of NRTIs compete with natural nucleotide pools for incorporation, and, once incorporated, the monophosphate acts as a chain terminator. NNRTIs bind to a hydrophobic pocket in the vicinity but not at the active site of HIV-1 RT. Previous studies have suggested that these compounds interfere with the chemical step, whereas nucleotide binding does not appear to be largely affected (2, 3). Here we studied the mechanism of action of the pyrophosphate (PP i ) analogue phosphonoformic acid (PFA or foscarnet), which represents a third class of RT inhibitors.PFA shows a broad spectrum of antiviral activities against various members of the Herpesviridae and Retroviridae (4). The inhibitor is used in the clinic to treat infection with herpes simplex virus type 1 and type 2 (HSV-1 and HSV-2), the human cytomegalovirus, and other related herpesviruses when firstline agents have failed (5). Toxic side effects and its poor bioavailability limit its clini...

show abstract

Mechanism by Which Phosphonoformic Acid Resistance Mutations Restore 3′-Azido-3′-deoxythymidine (AZT) Sensitivity to AZT-resistant HIV-1 Reverse Transcriptase

Cited by 55 publications

References 25 publications

Molecular Mechanism by Which the K70E Mutation in Human Immunodeficiency Virus Type 1 Reverse Transcriptase Confers Resistance to Nucleoside Reverse Transcriptase Inhibitors

Molecular Mechanism by Which the K70E Mutation in Human Immunodeficiency Virus Type 1 Reverse Transcriptase Confers Resistance to Nucleoside Reverse Transcriptase Inhibitors

Thymidine Analogue Resistance Suppression by V75I of HIV-1 Reverse Transcriptase

The Pyrophosphate Analogue Foscarnet Traps the Pre-translocational State of HIV-1 Reverse Transcriptase in a Brownian Ratchet Model of Polymerase Translocation

Contact Info

Product

Resources

About