1 research outputs found
Nanoscale Characterization of Interaction of APOBEC3G with RNA
The
human cytidine deaminase APOBEC3G (A3G) is a potent inhibitor
of the HIV-1 virus in the absence of viral infectivity factor (Vif).
The molecular mechanism of A3G antiviral activity is primarily attributed
to deamination of single-stranded DNA (ssDNA); however, the nondeamination
mechanism also contributes to HIV-1 restriction. The interaction of
A3G with ssDNA and RNA is required for its antiviral activity. Here
we used atomic force microscopy to directly visualize A3G–RNA
and A3G–ssDNA complexes and compare them to each other. Our
results showed that A3G in A3G–RNA complexes exists primarily
in monomeric–dimeric states, similar to its stoichiometry in
complexes with ssDNA. New A3G–RNA complexes in which A3G binds
to two RNA molecules were identified. These data suggest the existence
of two separate RNA binding sites on A3G. Such complexes were not
observed with ssDNA substrates. Time-lapse high-speed atomic force
microscopy was applied to characterize the dynamics of the complexes.
The data revealed that the two RNA binding sites have different affinities
for A3G. On the basis of the obtained results, a model for the interaction
of A3G with RNA is proposed