Insights into DNA substrate selection by APOBEC3G from structural, biochemical, and functional studies
A) Relative single-cycle infectivity of VSV-G-psuedotyped HIV-1Δvif viruses produced in the presence or absence of A3G-WT or A3G-P210R. Mean of two independent experiments done in triplicates are shown relative to the “no A3G” control (set to 100%); error bars, standard deviation. B and C) Effect of A3G-P210R substitution on the relative mutation frequencies at the +1 position nucleotide (b) and the -2 position nucleotide (c) with the preferred C at the -1 position (5’CC) or the non-preferred T at the -1 (5’TC) position. B) In the + 1 position nucleotide, mutation frequencies for the preferred sites with a C at -1 position (5’CC), A3G-WT prefers CCA or CCG over CCT and CCC; A3G-P210R prefers CCC over CCA, CCG, and CCT, but has no significant difference in preference between CCA and CCT. For the non-preferred sites with a T at -1 position (5’TC), A3G-WT and A3G-P210R both prefer TCA over TCT, TCG, or TCC. C) In the -2 position nucleotide, mutation frequencies for the preferred sites with a C at -1 position (5’CC), both A3G-WT and A3G-P210R prefer CCC over TCC, ACC, or GCC. For the non-preferred sites with a T at the -1 position (5’TC), A3G-WT prefers CTC over TTC, ATC, or GTC, whereas A3G-P210R prefers TTC or GTC over ATC and CTC. The significantly preferred nucleotide in the -2 or +1 positions are indicated (*P < 0.001). The number of sites, number of mutations, and relative mutation frequencies are shown in S1 Table.