RNA-binding proteins stabilize antiterminator structures.

<p>Alternative stem-loop structures in transcribed leader regions from representative operons are shown. Terminator stem regions that participate in alternative structures are in blue, whereas antiterminator regions are in red. (A) NasR-responsive <i>nasF</i> operon leader in termination conformation. Dots indicate the critical residues A1 and G4 in the P1 and P2 loops. (B) Each ANTAR monomer is hypothesized to bind one of the loops, P1 and P2. Stabilizing the P2 antiterminator structure permits transcription readthrough <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1002773#pgen.1002773-Ramesh1" target="_blank">[6]</a> by shortening the terminator stem and separating it from the poly-U tract <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1002773#pgen.1002773-Peters1" target="_blank">[2]</a>. (C) LicT-responsive <i>bglP</i> operon leader in termination conformation. RAT is the ribonucleic antiterminator. (D) Each CAT (co-antiterminator) monomer binds to the antiterminator stem. Unusual base-pairing within the antiterminator stem is depicted schematically <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1002773#pgen.1002773-Yang1" target="_blank">[25]</a>. Stablilizing the antiterminator structure permits transcription readthrough <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1002773#pgen.1002773-Houman1" target="_blank">[22]</a> by shortening the terminator stem and separating it from the poly-U tract.</p