CopA-like RNA is a family of non-coding RNA

Non-coding RNA

A non-coding RNA is a functional RNA molecule that is not translated into a protein. Less-frequently used synonyms are non-protein-coding RNA , non-messenger RNA and functional RNA . The term small RNA is often used for short bacterial ncRNAs...

s found on the R1 plasmid

R1 plasmid

The R1 Plasmid is a plasmid that was first isolated from Salmonella paratyphi bacteria in 1963.The R1 plasmid imparts multi-drug antibiotic resistance to its host bacteria....

.

In several groups of bacterial

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...

 plasmids, antisense RNAs regulate copy number

Gene copy number

Copy-number variations —a form of structural variation—are alterations of the DNA of a genome that results in the cell having an abnormal number of copies of one or more sections of the DNA. CNVs correspond to relatively large regions of the genome that have been deleted or duplicated on certain...

 through inhibition of replication initiator protein synthesis. These RNAs are characterised by a long hairpin structure

Stem-loop

Stem-loop intramolecular base pairing is a pattern that can occur in single-stranded DNA or, more commonly, in RNA. The structure is also known as a hairpin or hairpin loop. It occurs when two regions of the same strand, usually complementary in nucleotide sequence when read in opposite directions,...

 interrupted by several unpaired nucleotide

Nucleotide

Nucleotides are molecules that, when joined together, make up the structural units of RNA and DNA. In addition, nucleotides participate in cellular signaling , and are incorporated into important cofactors of enzymatic reactions...

s or bulged loops. In plasmid R1, the inhibitory complex between the antisense RNA (CopA) and its target mRNA (CopT) is characterised by a four-way junction structure

Holliday junction

A Holliday junction is a mobile junction between four strands of DNA. The structure is named after Robin Holliday, who proposed it in 1964 to account for a particular type of exchange of genetic information he observed in yeast known as homologous recombination...

and a side-by-side helical alignment.