Structural analysis of the Ψ–SL1region. (A) 1–561 RNA was probed with RNase T1 in the presence (lane 2) or absence (lane 3) of as548. The lanes labeled G, U, A, and C are sequencing lanes. (Lane 1) Control (1–561RNA primer extended without RNase T1 modification); (lane 2) 1–561RNA activated with oligonucleotide as548 during RNase T1 probing; (and lane 3) RNase T1 probing of 1–561RNA without as548 present during modification. Theregion labeled Ψ represents the palindromic sequence GGAGUGCUCC present in this region.The region labeled SL1represents the palindromic sequence GGUACC present in this region.(B) A model representing HIV-2 RNA SL1in an extended duplex conformation. (Open triangles) Cleavages observed in 1–561RNA by RNase T1 in the absence of as548. (Solid circles) RNase T1 cleavages observed in 1–561RNA with as548 present. An increase in nucleotide reactivity is represented by an increase in the symbol present at that location.
