Document 0424
 DOCN  M9460424
 TI    Mutagenicity and pausing of HIV reverse transcriptase during HIV
       plus-strand DNA synthesis.
 DT    9404
 AU    Ji J; Hoffmann JS; Loeb L; Joseph Gottstein Memorial Cancer Research
       Laboratory, Department; of Pathology SM-30, University of Washington,
       Seattle 98195.
 SO    Nucleic Acids Res. 1994 Jan 11;22(1):47-52. Unique Identifier : AIDSLINE
       MED/94173661
 AB    The unusually high frequency of misincorporation by HIV-1 reverse
       transcriptase (HIV RT) is likely to be the major factor in the rapid
       accumulation of viral mutations in AIDS, especially in the env gene. To
       investigate the ability of HIV RT to copy the env gene, we subcloned an
       HIV env gene fragment into a single-stranded DNA vector and measured the
       progression of synthesis by HIV RT. We observed that HIV RT, but not RT
       from avian myeloblastosis virus, DNA polymerase-alpha or T7 DNA
       polymerase, pauses specifically at poly-deoxyadenosine stretches within
       the env gene. The frequency of bypassing the polyadenosine stretches by
       HIV RT is enhanced by increasing the ratio of enzyme to template. We
       measured the fidelity of DNA synthesis within a segment of the
       hypervariable region 1 of the env gene (V-1) containing a
       poly-deoxyadenosine sequence by repetitively copying the DNA by HIV RT,
       and then cloning and sequencing the copied fragments. We found that 27%
       of the errors identified in V-1 sequence were frameshift mutations
       opposite the poly-adenosine tract, a site where strong pausing was
       observed. Pausing of HIV RT at the polyadenosine tract could be enhanced
       by either distamycin A or netropsin, (A-T)-rich minor groove binding
       peptides. Moreover, netropsin increases the frequency of frameshift
       mutations in experiments in which HIV RT catalyzes gap filling synthesis
       within the lacZ gene in double-stranded circular M13mp2 DNA. These
       combined results suggest that the enhanced mutation frequency may be due
       to increased pausing at netropsin-modified polyadenosine tracts.
       Therefore, netropsin and related A-T binding chemicals may selectively
       enhance frameshift mutagenesis induced by HIV RT and yield predominantly
       non-viable virus.
 DE    Base Composition  Base Sequence  Distamycins/PHARMACOLOGY  DNA,
       Viral/*BIOSYNTHESIS  *Genes, env  HIV-1/*ENZYMOLOGY  In Vitro  Molecular
       Sequence Data  Mutagenesis  Netropsin/PHARMACOLOGY  Poly A/METABOLISM
       Reverse Transcriptase/*METABOLISM  Substrate Specificity  Support, U.S.
       Gov't, P.H.S.  Templates  Virus Replication  JOURNAL ARTICLE

       SOURCE: National Library of Medicine.  NOTICE: This material may be
       protected by Copyright Law (Title 17, U.S.Code).