Abstract
Effective antiviral agents are thought to inhibit hepatitis B virus (HBV) DNA synthesis iirreversibly by chain termination because reverse transcriptases (RT) lack an exonucleolytic activity that can remove incorporated nucleotides. However, since the parameters governing this inhibition are poorly defined, fully delineating the catalytic mechanism of the HBV-RT promises to facilitate the development of antiviral drugs for treating chronic HBV infection. To this end, pyrophosphorolysis and pyrophosphate exchange, two nonhydrolytic RT activities that result in the removal of newly incorporated nucleotides, were characterized by using endogenous avian HBV replication complexes assembled in vivo. Although these activities are presumed to be physiologically irrelevant for every polymerase examined, the efficiency with which they are catalyzed by the avian HBV-RT strongly suggests that it is the first known polymerase to catalyze these reactions under replicative conditions. The ability to remove newly incorporated nucleotides during replication has important biological and clinical implications: these activities may serve a primer-unblocking function in vivo. Analysis of pyrophosphorolysis on chain-terminated DNA revealed that the potent anti-HBV drug β-L-(-)-2′,3′-dideoxy-3′thiacytidine (3TC) was difficult to remove by pyrophosphorolysis, in contrast to ineffective chain terminators such as ddC. This disparity may account for the strong antiviral efficacy of 3TC versus that of ddC. The HBV-RT pyrophosphorolytic activity may therefore be a novel determinant of antiviral drug efficacy, and could serve as a target for future antiviral drug therapy. The strong inhibitory effect of cytoplasmic pyrophosphate concentrations on viral DNA synthesis may also partly account for the apparent slow rate of HBV genome replication.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 4984-4989 |
| Number of pages | 6 |
| Journal | Proceedings of the National Academy of Sciences of the United States of America |
| Volume | 98 |
| Issue number | 9 |
| DOIs | |
| State | Published - Apr 24 2001 |
| Externally published | Yes |
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Keywords
- Antiviral inhibition
- Core particles
- Lamivudine/3TC
- Proofreading
ASJC Scopus subject areas
- Genetics
- General
Cite this
Efficient pyrophosphorolysis by a hepatitis B virus polymerase may be a primer-unblocking mechanism. / Urban, Sinisa; Urban, Severin; Fischer, Karl P.; Tyrrell, D. Lorne.
In: Proceedings of the National Academy of Sciences of the United States of America, Vol. 98, No. 9, 24.04.2001, p. 4984-4989.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Efficient pyrophosphorolysis by a hepatitis B virus polymerase may be a primer-unblocking mechanism
AU - Urban, Sinisa
AU - Urban, Severin
AU - Fischer, Karl P.
AU - Tyrrell, D. Lorne
PY - 2001/4/24
Y1 - 2001/4/24
N2 - Effective antiviral agents are thought to inhibit hepatitis B virus (HBV) DNA synthesis iirreversibly by chain termination because reverse transcriptases (RT) lack an exonucleolytic activity that can remove incorporated nucleotides. However, since the parameters governing this inhibition are poorly defined, fully delineating the catalytic mechanism of the HBV-RT promises to facilitate the development of antiviral drugs for treating chronic HBV infection. To this end, pyrophosphorolysis and pyrophosphate exchange, two nonhydrolytic RT activities that result in the removal of newly incorporated nucleotides, were characterized by using endogenous avian HBV replication complexes assembled in vivo. Although these activities are presumed to be physiologically irrelevant for every polymerase examined, the efficiency with which they are catalyzed by the avian HBV-RT strongly suggests that it is the first known polymerase to catalyze these reactions under replicative conditions. The ability to remove newly incorporated nucleotides during replication has important biological and clinical implications: these activities may serve a primer-unblocking function in vivo. Analysis of pyrophosphorolysis on chain-terminated DNA revealed that the potent anti-HBV drug β-L-(-)-2′,3′-dideoxy-3′thiacytidine (3TC) was difficult to remove by pyrophosphorolysis, in contrast to ineffective chain terminators such as ddC. This disparity may account for the strong antiviral efficacy of 3TC versus that of ddC. The HBV-RT pyrophosphorolytic activity may therefore be a novel determinant of antiviral drug efficacy, and could serve as a target for future antiviral drug therapy. The strong inhibitory effect of cytoplasmic pyrophosphate concentrations on viral DNA synthesis may also partly account for the apparent slow rate of HBV genome replication.
AB - Effective antiviral agents are thought to inhibit hepatitis B virus (HBV) DNA synthesis iirreversibly by chain termination because reverse transcriptases (RT) lack an exonucleolytic activity that can remove incorporated nucleotides. However, since the parameters governing this inhibition are poorly defined, fully delineating the catalytic mechanism of the HBV-RT promises to facilitate the development of antiviral drugs for treating chronic HBV infection. To this end, pyrophosphorolysis and pyrophosphate exchange, two nonhydrolytic RT activities that result in the removal of newly incorporated nucleotides, were characterized by using endogenous avian HBV replication complexes assembled in vivo. Although these activities are presumed to be physiologically irrelevant for every polymerase examined, the efficiency with which they are catalyzed by the avian HBV-RT strongly suggests that it is the first known polymerase to catalyze these reactions under replicative conditions. The ability to remove newly incorporated nucleotides during replication has important biological and clinical implications: these activities may serve a primer-unblocking function in vivo. Analysis of pyrophosphorolysis on chain-terminated DNA revealed that the potent anti-HBV drug β-L-(-)-2′,3′-dideoxy-3′thiacytidine (3TC) was difficult to remove by pyrophosphorolysis, in contrast to ineffective chain terminators such as ddC. This disparity may account for the strong antiviral efficacy of 3TC versus that of ddC. The HBV-RT pyrophosphorolytic activity may therefore be a novel determinant of antiviral drug efficacy, and could serve as a target for future antiviral drug therapy. The strong inhibitory effect of cytoplasmic pyrophosphate concentrations on viral DNA synthesis may also partly account for the apparent slow rate of HBV genome replication.
KW - Antiviral inhibition
KW - Core particles
KW - Lamivudine/3TC
KW - Proofreading
UR - http://www.scopus.com/inward/record.url?scp=0035942275&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0035942275&partnerID=8YFLogxK
U2 - 10.1073/pnas.091324398
DO - 10.1073/pnas.091324398
M3 - Article
C2 - 11320247
AN - SCOPUS:0035942275
VL - 98
SP - 4984
EP - 4989
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
SN - 0027-8424
IS - 9
ER -