The Lacto-usp RNA motif is a conserved RNA

RNA

Ribonucleic acid , or RNA, is one of the three major macromolecules that are essential for all known forms of life....

 structure identified in bacteria

Bacteria

Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...

 by bioinformatics

Bioinformatics

Bioinformatics is the application of computer science and information technology to the field of biology and medicine. Bioinformatics deals with algorithms, databases and information systems, web technologies, artificial intelligence and soft computing, information and computation theory, software...

. Lacto-usp RNAs are found exclusively in lactic acid bacteria

Lactic acid bacteria

The lactic acid bacteria comprise a clade of Gram-positive, low-GC, acid-tolerant, generally non-sporulating, non-respiring rod or cocci that are associated by their common metabolic and physiological characteristics. These bacteria, usually found in decomposing plants and lactic products, produce...

, and exclusively in the possible 5' untranslated regions of (5' UTRs) operon

Operon

In genetics, an operon is a functioning unit of genomic DNA containing a cluster of genes under the control of a single regulatory signal or promoter. The genes are transcribed together into an mRNA strand and either translated together in the cytoplasm, or undergo trans-splicing to create...

s that contain a hypothetical gene

Gene

A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...

 and a usp gene. The usp gene encodes the universal stress protein. It was proposed that the Lacto-usp might correspond to the 6S RNA

6S / SsrS RNA

6S RNA was the first noncoding RNA to be sequenced, but its function was unknown until recently. It consists of 184 nucleotides that fold into an extended hairpin structure with a large single-stranded internal bulge....

of the relevant species, because four of five of these species lack a predicted 6S RNA, and 6S RNAs commonly occur in 5' UTRs of usp genes. However, given that the Lacto-usp RNA motif is much shorter than the standard 6S RNA structure, the function of Lacto-usp RNAs remains unclear.