7w1r
Crystal structure of human Suv3 monomer
Structural highlights
FunctionSUV3_HUMAN Major helicase player in mitochondrial RNA metabolism. Component of the mitochondrial degradosome (mtEXO) complex, that degrades 3' overhang double-stranded RNA with a 3'-to-5' directionality in an ATP-dependent manner. ATPase and ATP-dependent multisubstrate helicase, able to unwind double-stranded (ds) DNA and RNA, and RNA/DNA heteroduplexes in the 5'-to-3' direction. Plays a role in the RNA surveillance system in mitochondria; regulates the stability of mature mRNAs, the removal of aberrantly formed mRNAs and the rapid degradation of non coding processing intermediates. Also implicated in recombination and chromatin maintenance pathways. May protect cells from apoptosis. Associates with mitochondrial DNA.[1] [2] [3] [4] [5] [6] [7] Publication Abstract from PubMedHuman Suv3 is a unique homodimeric helicase that constitutes the major component of the mitochondrial degradosome to work cooperatively with exoribonuclease PNPase for efficient RNA decay. However, the molecular mechanism of how Suv3 is assembled into a homodimer to unwind RNA remains elusive. Here, we show that dimeric Suv3 preferentially binds to and unwinds DNA-DNA, DNA-RNA, and RNA-RNA duplexes with a long 3' overhang (>/=10 nucleotides). The C-terminal tail (CTT)-truncated Suv3 (Suv3DeltaC) becomes a monomeric protein that binds to and unwinds duplex substrates with ~six to sevenfold lower activities relative to dimeric Suv3. Only dimeric Suv3, but not monomeric Suv3DeltaC, binds RNA independently of ATP or ADP, and is capable of interacting with PNPase, indicating that dimeric Suv3 assembly ensures its continuous association with RNA and PNPase during ATP hydrolysis cycles for efficient RNA degradation. We further determined the crystal structure of the apo-form of Suv3DeltaC, and SAXS structures of dimeric Suv3 and PNPase-Suv3 complex, showing that dimeric Suv3 caps on the top of PNPase via interactions with S1 domains, and forms a dumbbell-shaped degradosome complex with PNPase. Overall, this study reveals that Suv3 is assembled into a dimeric helicase by its CTT for efficient and persistent RNA binding and unwinding to facilitate interactions with PNPase, promote RNA degradation, and maintain mitochondrial genome integrity and homeostasis. Dimeric assembly of human Suv3 helicase promotes its RNA unwinding function in mitochondrial RNA degradosome for RNA decay.,Jain M, Golzarroshan B, Lin CL, Agrawal S, Tang WH, Wu CJ, Yuan HS Protein Sci. 2022 May;31(5):e4312. doi: 10.1002/pro.4312. PMID:35481630[8] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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