PMID: 21297639

Authors:

Chang JH, Xiang S, Xiang K, Manley JL, Tong L

Title:

Structural and biochemical studies of the 5'-->3' exoribonuclease Xrn1.

Journal:

Nat Struct Mol Biol. 2011 Mar;18(3):270-6. doi: 10.1038/nsmb.1984. Epub 2011 Feb , 6.

Abstract:

The 5'-->3' exoribonucleases (XRNs) have important functions in transcription, RNA metabolism and RNA interference. The structure of Rat1 (also known as Xrn2) showed that the two highly conserved regions of XRNs form a single, large domain that defines the active site of the enzyme. Xrn1 has a 510-residue segment after the conserved regions that is required for activity but is absent from Rat1/Xrn2. Here we report the crystal structures of Kluyveromyces lactis Xrn1 (residues 1-1,245, E178Q mutant), alone and in complex with a Mn(2+) ion in the active site. The 510-residue segment contains four domains (D1-D4), located far from the active site. Our mutagenesis and biochemical studies show that their functional importance results from their ability to stabilize the conformation of the N-terminal segment of Xrn1. These domains might also constitute a platform that interacts with protein partners of Xrn1.