The OmrA-B RNA gene family (also known as SraE RNA, RygA and RygB and OmrA and OmrB) is a pair of homologous OmpR-regulated small non-coding RNA that was discovered in E. coli during two large-scale screens.

[1][2] OmrA-B is highly abundant in stationary phase, but low levels could be detected in exponentially growing cells as well.

RygB is adjacent to RygA a closely related RNA.

They negatively regulate the expression of several genes encoding outer membrane proteins, including cirA, CsgD, fecA, fepA and ompT by binding in the vicinity of the Shine-Dalgarno sequence, suggesting the control of these targets is dependent on Hfq protein and RNase E. Taken together, these data suggest that OmrA-B participates in the regulation of outer membrane composition, responding to environmental conditions.

[3][4][5] Together with the RNA chaperone Hfq, OmrA-B positively controls bacterial motility and negatively controls the production of acidic exopolysaccharide amylovoran in plant pathogen Erwinia amylovora.