RRNAt

rRNAt is a term used in some microbiology literature to refer to small, noncoding RNA elements associated with ribosomal RNA (rRNA) transcription. The acronym stands for ribosomal RNA transcription-associated RNA and is not universally standardized; definitions vary between studies.

Reportedly, rRNAt elements are located within or near rrn operons in bacteria, and in some archaeal genomes. Their expression can be condition-dependent, and they may be produced from processing of primary rRNA transcripts or from independent promoters.

These RNAs are described as short noncoding transcripts, often in the range of 50 to 250 nucleotides. They are predicted to fold into simple secondary structures such as hairpins, and some studies report conserved sequence motifs across taxa, suggesting functional constraints.

Proposed functions for rRNAt include modulation of transcription termination at rrn operons, facilitation of rRNA maturation, or regulation of rRNA gene expression in response to stress. However, the evidence is preliminary and context-dependent, and the exact roles remain uncertain.

Research on rRNAt typically employs RNA sequencing and northern blot analyses to detect transcripts, with functional validation being limited. Because some rRNAt transcripts overlap with rRNA sequences, there is ongoing discussion about whether they represent independent functional RNAs or degradation products, though other findings point to specific interactions with RNA-binding proteins.

See also: small regulatory RNAs, noncoding RNAs, rrn operon.