Structural Basis for the Bidirectional Activity of Bacillus nanoRNase NrnA

Brad J. Schmier, Claudiu M. Nelersa, Arun Malhotra

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


NanoRNAs are RNA fragments 2 to 5 nucleotides in length that are generated as byproducts of RNA degradation and abortive transcription initiation. Cells have specialized enzymes to degrade nanoRNAs, such as the DHH phosphoesterase family member NanoRNase A (NrnA). This enzyme was originally identified as a 3′ → 5′ exonuclease, but we show here that NrnA is bidirectional, degrading 2-5 nucleotide long RNA oligomers from the 3′ end, and longer RNA substrates from the 5′ end. The crystal structure of Bacillus subtilis NrnA reveals a dynamic bi-lobal architecture, with the catalytic N-terminal DHH domain linked to the substrate binding C-terminal DHHA1 domain via an extended linker. Whereas this arrangement is similar to the structure of RecJ, a 5′ → 3′ DHH family DNase and other DHH family nanoRNases, Bacillus NrnA has gained an extended substrate-binding patch that we posit is responsible for its 3′ → 5′ activity.

Original languageEnglish (US)
Article number11085
JournalScientific reports
Issue number1
StatePublished - Dec 1 2017

ASJC Scopus subject areas

  • General


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