Prevotella-2 RNA motif
The "Prevotella"-2 RNA motif is a conserved RNA structure that was discovered by bioinformatics. Energetically stable tetraloops often occur in this motif. "Prevotella"-2 motif RNAs are found in the bacterial genus "Prevotella". Nearly all "Prevotella"-2 RNAs occur upstream of genes that encode sodium/proton antiporters. These data suggest that the RNAs function as cis-regulatory elements. However, one "Prevotella"-2 RNA is located upstream of a gene encoded on the opposite DNA strand, which would be unlikely for a "cis"-regulatory function in bacteria. Therefore, it is also possible that "Prevotella"-2 RNAs are small RNAs that operate in "trans . In this model, their association with sodium/proton antiporters would be a coincidence. Most Prevotella"-2 RNAs are followed by a Rho-independent transcription terminator. If the RNAs function in "cis", these transcript terminators might be a part of the mechanism used to achieve gene regulation. If, on the other hand, "Prevotella"-2 RNAs correspond to small RNAs, the terminators may simply terminate the transcript containing this non-coding RNA.