Figure 3. RNA binding on the distal surface of Hfq. (A) Recognition of an RNA with a (5′-ANA-3′)₆ signature on EcHfq.³⁸ Transparent surfaces of Hfq protomers are colored in white and gray and numbered counterclockwise to relate the arrangement to Figure 2. RNA is shown as sticks with a backbone cartoon that is colored with a gradient from light to dark blue to indicate the 5′-3′ direction. Nucleotides that reside in specific binding pockets are in dark red (conserved “R”-site) and light red (‘A’-site for the second linker nucleotide), the unbound linker nucleotide is in blue. (B) Recognition of an RNA with a (5′-AN-3′)₆ signature on BsHfq,³⁹ a representative from a gram-positive bacterium. Nucleotides that reside in specific binding pockets are in dark red (conserved “R”-site), the unbound linker nucleotide is in blue.