TY - JOUR
T1 - APOBEC3G inhibits HIV-1 RNA elongation by inactivating the viral trans-activation response element
AU - Nowarski, Roni
AU - Prabhu, Ponnandy
AU - Kenig, Edan
AU - Smith, Yoav
AU - Britan-Rosich, Elena
AU - Kotler, Moshe
PY - 2014/7/29
Y1 - 2014/7/29
N2 - Deamination of cytidine residues in viral DNA is a major mechanism by which APOBEC3G (A3G) inhibits vif-deficient human immunodeficiency virus type 1 (HIV-1) replication. dC-to-dU transition following RNase-H activity leads to viral cDNA degradation, production of non-functional proteins, formation of undesired stop codons and decreased viral protein synthesis. Here, we demonstrate that A3G provides an additional layer of defense against HIV-1 infection dependent on inhibition of proviral transcription. HIV-1 transcription elongation is regulated by the trans-activation response (TAR) element, a short stem-loop RNA structure required for elongation factors binding. Vif-deficient HIV-1-infected cells accumulate short viral transcripts and produce lower amounts of full-length HIV-1 transcripts due to A3G deamination of the TAR apical loop cytidine, highlighting the requirement for TAR loop integrity in HIV-1 transcription. We further show that free single-stranded DNA (ssDNA) termini are not essential for A3G activity and a gap of CCC motif blocked with juxtaposed DNA or RNA on either or 3′ + 5′ ends is sufficient for A3G deamination. These results identify A3G as an efficient mutator and that deamination of (-)SSDNA results in an early block of HIV-1 transcription.
AB - Deamination of cytidine residues in viral DNA is a major mechanism by which APOBEC3G (A3G) inhibits vif-deficient human immunodeficiency virus type 1 (HIV-1) replication. dC-to-dU transition following RNase-H activity leads to viral cDNA degradation, production of non-functional proteins, formation of undesired stop codons and decreased viral protein synthesis. Here, we demonstrate that A3G provides an additional layer of defense against HIV-1 infection dependent on inhibition of proviral transcription. HIV-1 transcription elongation is regulated by the trans-activation response (TAR) element, a short stem-loop RNA structure required for elongation factors binding. Vif-deficient HIV-1-infected cells accumulate short viral transcripts and produce lower amounts of full-length HIV-1 transcripts due to A3G deamination of the TAR apical loop cytidine, highlighting the requirement for TAR loop integrity in HIV-1 transcription. We further show that free single-stranded DNA (ssDNA) termini are not essential for A3G activity and a gap of CCC motif blocked with juxtaposed DNA or RNA on either or 3′ + 5′ ends is sufficient for A3G deamination. These results identify A3G as an efficient mutator and that deamination of (-)SSDNA results in an early block of HIV-1 transcription.
KW - APOBEC3G
KW - deamination
KW - HIV-1
KW - ssDNA
KW - Tat
UR - http://www.scopus.com/inward/record.url?scp=84904166821&partnerID=8YFLogxK
U2 - 10.1016/j.jmb.2014.05.012
DO - 10.1016/j.jmb.2014.05.012
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C2 - 24859335
AN - SCOPUS:84904166821
SN - 0022-2836
VL - 426
SP - 2840
EP - 2853
JO - Journal of Molecular Biology
JF - Journal of Molecular Biology
IS - 15
ER -