The ''terC'' RNA motif is a conserved

RNA Ribonucleic acid (RNA) is a polymeric molecule that is essential for most biological functions, either by performing the function itself (non-coding RNA) or by forming a template for the production of proteins (messenger RNA). RNA and deoxyrib ...

structure that was discovered by bioinformatics. ''terC'' motif RNAs are found in

Pseudomonadota Pseudomonadota (synonym "Proteobacteria") is a major phylum of gram-negative bacteria. Currently, they are considered the predominant phylum within the domain of bacteria. They are naturally found as pathogenic and free-living (non- parasitic) ...

, within the sub-lineages

Alphaproteobacteria ''Alphaproteobacteria'' or ''α-proteobacteria'', also called ''α-Purple bacteria'' in earlier literature, is a class of bacteria in the phylum '' Pseudomonadota'' (formerly "Proteobacteria"). The '' Magnetococcales'' and '' Mariprofundales'' ar ...

and

Pseudomonadales The Pseudomonadales are an order of Pseudomonadota. A few members are pathogens, such as species of ''Pseudomonas'', ''Moraxella'', and '' Acinetobacter'', which may cause disease in humans, animals and plants. ''Pseudomonas'' The bacterial genu ...

. ''terC'' motif RNAs likely function as

cis-regulatory element ''Cis''-regulatory elements (CREs) or ''cis''-regulatory modules (CRMs) are regions of non-coding DNA which regulate the transcription of neighboring genes. CREs are vital components of genetic regulatory networks, which in turn control morpho ...

s, in view of their positions upstream of protein-coding

gene In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protei ...

s. Indeed, the RNAs are upstream of multiple genes that encode non- homologous

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...

s. If all examples of the RNA were upstream of homologous genes, there is the possibility that the RNAs were conserved in that position simply by inheritance. The non-homology of the genes downstream of ''terC'' RNAs makes this scenario less likely. When considering the conserved

protein domain In molecular biology, a protein domain is a region of a protein's Peptide, polypeptide chain that is self-stabilizing and that Protein folding, folds independently from the rest. Each domain forms a compact folded Protein tertiary structure, thre ...

s contained in proteins that are encoded by ''terC''-regulated genes, the most frequent are classified as TIGR03717 and TIGR03718, according to the Conserved domain database. Both TIGR03717 and TIGR03718 are homologous with the

membrane A membrane is a selective barrier; it allows some things to pass through but stops others. Such things may be molecules, ions, or other small particles. Membranes can be generally classified into synthetic membranes and biological membranes. Bi ...

-bound protein known as TerC. TerC proteins are implicated in

tellurium Tellurium is a chemical element; it has symbol Te and atomic number 52. It is a brittle, mildly toxic, rare, silver-white metalloid. Tellurium is chemically related to selenium and sulfur, all three of which are chalcogens. It is occasionally fou ...

resistance. A separate conserved RNA, originally known as the

YybP-ykoY leader The yybP-ykoY leader RNA element was originally discovered in ''E. coli'' during a large scale screen and was named SraF. This family was later found to exist upstream of related families of protein genes in many bacteria, including the yybP a ...

, is now known to function as a

manganese Manganese is a chemical element; it has Symbol (chemistry), symbol Mn and atomic number 25. It is a hard, brittle, silvery metal, often found in minerals in combination with iron. Manganese was first isolated in the 1770s. It is a transition m ...

-sensing

riboswitch In molecular biology, a riboswitch is a regulatory segment of a messenger RNA molecule that binds a small molecule, resulting in a change in Translation (biology), production of the proteins encoded by the mRNA. Thus, an mRNA that contains a ribo ...

. Genes regulated by these manganese riboswitches very frequently encode proteins similar to TerC. In view of this association, it was proposed that ''terC'' RNAs might also function as riboswitches that sense an

ion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convent ...

similar to manganese. Experimental confirmation of this hypothesis is lacking. However, the conserved domain known as "COG3809" is also commonly regulated by ''terC'' RNAs as well as manganese riboswitches, providing another possible link between these conserved RNA structures.

References

{{reflist Non-coding RNA