Implications for OLE RNA as a natural integral membrane RNA.

Ornate, large, extremophilic (OLE) RNAs, found in many Gram-positive bacterial species, represent an unusual class of noncoding RNAs which form a large ribonucleoprotein complex that localizes to cell membranes. Although the precise biochemical functions of OLE RNAs remain to be discovered, several lines of evidence suggest that they participate in forming particles that function as the master regulators of their bacterial hosts. Thus, OLE RNA might be a molecular relic of RNA World organisms that contributed to cellular stress responses long before the evolutionary emergence of proteins. Recent reports of partial 3-D structures strongly suggest that OLE RNAs form a molecular dimer whose complex structure spans the phospholipid bilayer of membranes. The implications of these findings on the functions of OLE RNA and on the capabilities of RNA polymers more broadly are discussed.