NAD-I riboswitch
Conserved RNA structure
The NAD-I riboswitch (also known as the nadA RNA motif) is a conserved RNA structure found in bacteria, primarily within the phylum Acidobacteriota. All known NAD-I riboswitch representatives are located upstream of nadA genes, which encode quinolinate synthase, an enzyme that catalyzes an early step in the de novo biosynthetic pathway for NAD⁺. The nadA RNA motif was first identified through a comparative genomic search for structured noncoding RNAs (ncRNA) in bacterial intergenic regions.
Approximately two-thirds of all known bacterial riboswitch classes respond to compounds derived from RNA nucleotides, including cofactors such as thiamin pyrophosphate (TPP), flavin mononucleotide (FMN), adenosylcobalamin (AdoCbl), and S-adenosylmethionine (SAM). NAD⁺ is recognised as another ancient and ubiquitous nucleotide-derived coenzyme, were nadA RNA motif proved to acts as a riboswitch for the enzyme cofactor NAD+.
Structure
Tandem Aptamer Architecture
nadA motif RNAs invariably occur as a tandem pair of two highly similar aptamer domains, referred to as Domain 1 and Domain 2.
Each domain forms two base-paired stems P1 and P1a flanking a conserved internal bulge carrying the near-identical sequence "ACANCCCC". Domain 1 is further distinguished by an additional internal loop (sequence "AGYG") between P1a and a third stem, P1b. Domain 2 carries a purine-rich region in the right shoulder of stem P1′ predicted to serve as the ribosome binding site (RBS) for the downstream nadA open reading frame (ORF).
Expression Platform
The expression platform of NAD⁺-I riboswitches is predicted to operate as a translational "OFF" switch.
“NAD-I riboswitch” enters the record as conserved RNA structure. Crown Archives preserves that source wording while asking what NAD-I, riboswitch and Conserved can confirm, complicate or overturn.
Why this record matters
“NAD-I riboswitch” is worth following because a concise public description often conceals a longer documentary argument. Here, NAD-I, riboswitch and Conserved provides the most credible route into that argument.
Named sources, stable identifiers and responsible institutions provide the strongest route from overview to verifiable evidence. The source revision retrieved here is dated Mar 4, 2026. The linked authority identifier is Q56292504. None of the 0 selected statements returned an explicit reference.
Overview language is designed for orientation and should not be treated as a substitute for the evidence cited beneath it. The source lead contains qualifying language; that uncertainty should survive quotation, summary and reuse. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.
How to read it
Use the entry as an orientation point, then follow its citations and revision history. Names, dates and institutional relationships should be checked against the original record.
- Subject orientation
- Search vocabulary
- Locating named sources
The closest primary source, responsible institution and strongest cited specialist reference.
Three-step research path
- Establish the record: confirm the title “NAD-I riboswitch”, its source revision and the description used here.
- Expand the search: follow NAD-I riboswitch primary sources, NAD-I riboswitch archive and NAD-I research across catalogues and specialist indexes.
- Test the account: compare the strongest cited source with the responsible institution’s current record and note any disagreement.
Questions for further research
- Which source most directly establishes the central claim about “NAD-I riboswitch”?
- Which institution is responsible for the underlying evidence?
- What terminology or title could unlock a more precise catalogue search?
Search terms from this dossier
This entry incorporates text from “NAD-I riboswitch” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.