5ipp | pdb_00005ipp
Structure of Bacillus NanoRNase A active site mutant bound to a mononucleotide
Structural highlights
Function[NRNA_BACSU] Bifunctional enzyme which has both oligoribonuclease and pAp-phosphatase activities. Degrades RNA and DNA oligonucleotides with a length of 5 nucleotides and shorter, with a preference for 3-mers. Directionality is controversial; shown to degrade 5-mers and less in a 3' to 5' direction (PubMed:17586819), and 11-mers in a 5' to 3' direction (PubMed:21087930). Converts 3'(2')-phosphoadenosine 5'-phosphate (PAP) to AMP.[1] [2] [3] Publication Abstract from PubMedNanoRNAs 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. Structural Basis for the Bidirectional Activity of Bacillus nanoRNase NrnA.,Schmier BJ, Nelersa CM, Malhotra A Sci Rep. 2017 Sep 11;7(1):11085. doi: 10.1038/s41598-017-09403-x. PMID:28894100[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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