Pxr sRNA is a regulatory RNA which downregulates genes responsible for the formation of fruiting bodies in Myxococcus xanthus.

This finding implies that Pxr-S is specifically responsible for inhibiting the fruiting body development during cell growth when nutrients are abundant.

Homologs were not found in any other myxobacteria (such as Sorangium cellulosum[4] or Anaeromyxobacter dehalogenans[5]) which suggests the Pxr RNA gene may have a recent evolutionary origin in the sub-clade Myxococcales.

[7] The first mutation causes an obligate cheat (OC) phenotype to emerge, these bacteria exploit the fruiting bodies of wild-type M. xanthus to sporulate more efficiently.

[1] The PX phenotype was developmentally superior to both OC and wt, it was able to sporulate autonomously - without forming fruiting bodies and with high efficiency.