TABLE 2.

Effect of 16S rRNA mutations on HIV-1 programmed −1 frameshift

	Frameshift efficiency (%)
HIV constructs	Wild-type 16S rRNA	A900U	C899A/A900G	C912U
pRNAluc2-HIV35	0.8 ± 0.1	0.7 ± 0.2	0.6 ± 0.1	0.9 ± 0.2
pRNAluc2-HIV63	3.0 ± 0.4	2.3 ± 0.2	1.9 ± 0.2	3.3 ± 0.6
pRNAluc2-HIV80	4.8 ± 0.4	3.8 ± 0.4	2.3 ± 0.3	5.0 ± 0.6

Plasmids pRNAluc2-HIV35, pRNAluc2-HIV63, and pRNAluc2-HIV80 contain, respectively, only the slippery sequence, the slippery sequence plus the classic stem-loop, and the slippery sequence plus the complete frameshift stimulatory signal. The A900U, C899A/A900G, and C912U mutations are located in 16S rRNA. The A900U and the C899A/A900G mutations make the ribosomes errorprone (Bélanger et al. 2002), whereas the C912U mutation makes the ribosomes hyperaccurate (Leclerc et al. 1991). The frameshift efficiencies were calculated from luciferase activities in bacterial lysates as described in the text. The values are the means ± standard error of three independent experiments.