Anti small RNA

Antisense small RNA are found in all domains of life, including Eukaryotes, Bacteria and Archaea.^[14][15] They are non-coding RNA sequences involved in regulatory processes, such as metabolism and aiding in transcription.^[14] Many anti-sRNAs are involved in regulatory activities to modulate gene expression, with the bulk of research exploring specific interactions within the bacterial domain.^[16][17] One example of this is established in bacterial trans-encoded sRNA, which demonstrate only partial complementarity to the target RNA.^[18] These sRNA function to modulate base-pair interactions and translation by directly targeting the mRNA, thereby affecting its stability.^[19] Anti-sRNAs are able to interact with other sRNAs by targeting either the region involved in targeting the mRNA, or it can bind to another corresponding region along the sRNA.^[7] This has further been characterized in gene circuits that are sRNA-controlled and regulate aspects of bacterial pathogenesis.^[19]

Antisense small RNA can also be engineered and utilized by scientists to perform experimental functions.^[20] In synthetic biology, employing non-coding RNA such as antisense small RNA has advantages for creating regulatory architecture within engineering systems, provided the ability to predict function using the strand sequence.^[20] In experiments, engineered riboregulators, which are specific RNA that respond to signal RNA through complementary base pairing utilizing anti-small RNA, have been found to be capable of activating independent gene expression.^[20] Development of RNA array-based interaction assays that allow for screening in vitro have further advanced platforms targeting gene expression with antisense small RNAs.^[19][21] RNA-array based interaction assays screen for synthetic antisense small RNA interactions in vitro, through a surface-capture technique.^[19][21] An array of immobilized double-stranded DNA template for antisense small RNA sits opposite to an RNA-capture surface composed of possible antisense small RNA targets, separated by a solution of transcription reagents.^[19][21] Captured RNA are visualized using fluorescent staining, which can indicate whether a prospective antisense small RNA has been bound to its target.^[19][21]

Anti-bacterial targeting of V. cholerae occurs through the promotion of gene expression patterns that liberate bacteria from its host.^[19][21] This has been achieved by utilizing antisense small RNAs designed through the RNA array pipeline, opening the possibilities for future antimicrobial or therapeutic applications.^[19][21]

AsxR, previously known as EcOnc02, is an anti-sRNA encoded within the 3' region of the stx2B gene of E.Coli bacteria.^[1] It acts to increase expression of the ChuS heme oxygenase via destabilisation of FnrS sRNA.^[1] This aids bacterial infection of the animal host gut.^[1]

AgvB, previously known as EcOnc01, inhibits GcvB sRNA repression.^[1] Pathogenicity island associated AgvB aids enterohemorrhagic E. coli growth at the colonized site within the host animal.^[1] This bacterial growth often manifests into an increased risk of developing other conditions such as hemolytic uremic syndrome.

RosA, has been found to inhibit two sRNAs (RoxS and FsrA).^[22] Inhibition of RoxS by RosA plays a role in metabolism regulation, while FsrA is involved in maintaining iron availability for protein function.^[22] RosA is also the first antisense small RNA experimentally confirmed in Gram-positive bacteria.^[22]