sbRNA

sbRNA
Conserved secondary structure of nematode sbRNA
Identifiers
Symbol	sbRNA
Other data
RNA type	Gene
Domain(s)	Caenorhabditis
SO	{{{SO}}}

sbRNA (stem-bulge RNA) is a family of non-coding RNA first discovered in Caenorhabditis elegans. It was identified during a full transcriptome screen of the C. elegans cDNA library.^[1] Subsequent experimentation characterised sbRNA as having conserved 5' and 3' internal motifs which form a long paired stem which is interrupted with a bulge.^[2]

Expression

sbRNAs have variable expression patterns during development. They are most highly expressed in adult worms, dauer larvae and following heat shock.^[1] A systematic knockout analysis using RNAi found no phenotype for the knockout of two sbRNAs in C. elegans,^[3] however the efficiency of RNAi on ncRNA has been questioned.^[4] sbRNAs contain immunoglobulin in their protein fibers to maintain rigidity, however they are at risk of infection from malfunctioning ribosomes.

sbRNAs share common promoter elements consisting of a TATA box and a proximal sequence element (PSE B box), though only one of these is required for transcription.^[5] As the transcript is uncapped and polyuridylated, it is thought to be transcribed by RNA polymerase III.^[6]

Y RNA homology

An sbRNA, CeN134 was reported as a candidate homologue to the vertebrate Y RNA during a kingdom-wide search.^[7] Further investigation found a homologous secondary structure with a conserved helical regions and a common UUAUC loop motif.^[6]

The function of sbRNAs may therefore be similar to that of vertebrate Y RNAs, namely acting as part of the Ro-RNA particle to control RNA quality^[8] and playing a role in chromosomal replication.^[9] Deletion of sbRNA does not prevent chromosome replication in C. elegans, but this may be a result of other sbRNAs substituting missing elements (as in human Y RNA). This theory also explains why RNAi studies failed to detect a phenotype for knocked out sbRNAs.^[6]

See also

• Y RNA

References

Further reading