Suv3 (CG9791) is the Drosophila ortholog of the mitochondrial Ski2-like DExH-box RNA helicase SUPV3L1. It is an ATP-dependent helicase that resides in mitochondria and, with polynucleotide phosphorylase (PNPase), forms the mitochondrial degradosome that degrades mitochondrial mRNAs and antisense transcripts. Independently of PNPase, Suv3 is required for efficient processing of polycistronic mitochondrial transcripts, so its loss depletes mitochondrial tRNAs, accumulates precursor RNAs and mRNAs, reduces mitochondrial translation and respiratory chain activity, and causes lethality.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0000957 mitochondrial RNA catabolic process | IMP PMID:26152302 SUV3 helicase is required for correct processing of mitochon... | ACCEPT | Summary: Suv3 is required for mitochondrial RNA decay. Reason: Loss of DmSUV3 stabilizes mitochondrial mRNAs and antisense RNAs, in cooperation with PNPase. Supporting Evidence: PMID:26152302 Loss of dmsuv3 led to the accumulation of mitochondrial mRNAs, without increasing rRNA levels, de novo transcription or decay intermediates PMID:31365523 Besides degrading mRNAs, loss of the degradosome also resulted in the accumulation of antisense RNA, suggesting that PNPase and SUV3 are also responsible for degrading these RNAs |
| GO:0000957 mitochondrial RNA catabolic process | IMP PMID:31365523 Defects of mitochondrial RNA turnover lead to the accumulati... | ACCEPT | Summary: Suv3 is required for mitochondrial RNA decay. Reason: Loss of DmSUV3 stabilizes mitochondrial mRNAs and antisense RNAs, in cooperation with PNPase. Supporting Evidence: PMID:26152302 Loss of dmsuv3 led to the accumulation of mitochondrial mRNAs, without increasing rRNA levels, de novo transcription or decay intermediates PMID:31365523 Besides degrading mRNAs, loss of the degradosome also resulted in the accumulation of antisense RNA, suggesting that PNPase and SUV3 are also responsible for degrading these RNAs |
| GO:0000963 mitochondrial RNA processing | IMP PMID:26152302 SUV3 helicase is required for correct processing of mitochon... | ACCEPT | Summary: Suv3 is required for processing of polycistronic mitochondrial transcripts. Reason: DmSUV3 knockdown depletes mitochondrial tRNAs and causes accumulation of unprocessed precursors. Supporting Evidence: PMID:26152302 we observed a severe decrease in mitochondrial tRNAs accompanied by an accumulation of unprocessed precursor transcripts PMID:26152302 our results propose that SUV3 is predominantly required for the processing of mitochondrial polycistronic transcripts in metazoan and that this function is independent of PNPase |
| GO:0000965 mitochondrial RNA 3'-end processing | IBA GO_REF:0000033 | ACCEPT | Summary: Mitochondrial RNA 3'-end processing. Reason: Precursors with unprocessed 3' tRNA junctions accumulate in DmSUV3-knockdown larvae; consistent with the conserved family role. Propagation Review Root cause: NO FAILURE CORE Sources checked: PANTHER:PTN000252978 SUPPORTS TRANSFER Suv3 is the single fly SUPV3L1 ortholog; fly genetics confirm a precursor-processing role. Supporting Evidence: PMID:26152302 We found a significant accumulation of the 5′ and 3′ junctions of tRNATrp, tRNACys and tRNATyr (Figure 5D and E) and the 3′ junction of tRNAGln |
| GO:0003678 DNA helicase activity | ISS GO_REF:0000024 | MARK AS OVER ANNOTATED | Summary: DNA helicase activity inferred from human SUPV3L1. Reason: Human SUPV3L1 unwinds DNA duplexes in vitro, but the in vivo role of Suv3 in flies is in mitochondrial RNA processing and decay, and no DmSUV3 DNA unwinding or DNA-metabolism phenotype has been reported (no purified fly protein has been assayed for duplex unwinding); fly Suv3 also does not localize to the nucleus. The UniProt FUNCTION text cited for the RNA helicase row also mentions dsDNA unwinding, but that statement is transferred from the human protein. Supporting Evidence: PMID:26152302 Surprisingly, we observed no nuclear localization. |
| GO:0003724 RNA helicase activity | IEA GO_REF:0000120 | ACCEPT | Summary: Suv3 is an RNA helicase. Reason: Core molecular activity; Suv3 is an ATP-dependent Ski2-like helicase acting on mitochondrial RNA. The UniProt sentence quoted below also lists dsDNA unwinding (from human SUPV3L1); only the RNA part is accepted here, see the GO:0003678 row. Supporting Evidence: file:DROME/Suv3/Suv3-uniprot.txt 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 PMID:26152302 our results propose that SUV3 is predominantly required for the processing of mitochondrial polycistronic transcripts in metazoan and that this function is independent of PNPase |
| GO:0005524 ATP binding | IEA GO_REF:0000002 | ACCEPT | Summary: ATP binding (InterPro). Reason: DExH-box helicase P-loop. Supporting Evidence: file:DROME/Suv3/Suv3-uniprot.txt 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 |
| GO:0005739 mitochondrion | IDA PMID:26152302 SUV3 helicase is required for correct processing of mitochon... | ACCEPT | Summary: Suv3 is mitochondrial. Reason: DmSUV3-GFP colocalizes with mitochondrial markers without nuclear signal. Supporting Evidence: PMID:26152302 DmSUV3 shows clear mitochondrial localization |
| GO:0005739 mitochondrion | IEA GO_REF:0000044 | ACCEPT | Summary: Suv3 is mitochondrial. Reason: DmSUV3-GFP colocalizes with mitochondrial markers without nuclear signal. Supporting Evidence: PMID:26152302 DmSUV3 shows clear mitochondrial localization |
| GO:0005759 mitochondrial matrix | ISS GO_REF:0000024 | ACCEPT | Summary: Suv3 is in the mitochondrial matrix. Reason: Acts on mitochondrial transcripts in the matrix with PNPase. Supporting Evidence: PMID:26152302 Studies in yeast and human cell lines have indicated that the mitochondrial helicase SUV3, together with the polynucleotide phosphorylase, PNPase, composes the mitochondrial degradosome |
| GO:0016887 ATP hydrolysis activity | IEA GO_REF:0000116 | ACCEPT | Summary: Suv3 hydrolyses ATP. Reason: ATP hydrolysis drives helicase unwinding. Supporting Evidence: file:DROME/Suv3/Suv3-uniprot.txt 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 |
| GO:0016887 ATP hydrolysis activity | ISS GO_REF:0000024 | ACCEPT | Summary: Suv3 hydrolyses ATP. Reason: ATP hydrolysis drives helicase unwinding. Supporting Evidence: file:DROME/Suv3/Suv3-uniprot.txt 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 |
| GO:0045025 mitochondrial degradosome | IBA GO_REF:0000033 | ACCEPT | Summary: Suv3 is part of the mitochondrial degradosome. Reason: SUV3 with PNPase forms the degradosome; fly genetics show SUV3/PNPase-dependent decay of mRNAs and antisense RNAs. Propagation Review Root cause: NO FAILURE CORE Sources checked: PANTHER:PTN000252978 SUPPORTS TRANSFER Degradosome membership is conserved from yeast to human and supported by fly genetic interaction data. Supporting Evidence: PMID:26152302 Studies in yeast and human cell lines have indicated that the mitochondrial helicase SUV3, together with the polynucleotide phosphorylase, PNPase, composes the mitochondrial degradosome PMID:31365523 are therefore rapidly degraded in a SUV3/PNPase-dependent manner |
| GO:0045025 mitochondrial degradosome | IGI PMID:31365523 Defects of mitochondrial RNA turnover lead to the accumulati... | ACCEPT | Summary: Suv3 is part of the mitochondrial degradosome. Reason: SUV3 with PNPase forms the degradosome; fly genetics show SUV3/PNPase-dependent decay of mRNAs and antisense RNAs. Supporting Evidence: PMID:26152302 Studies in yeast and human cell lines have indicated that the mitochondrial helicase SUV3, together with the polynucleotide phosphorylase, PNPase, composes the mitochondrial degradosome PMID:31365523 are therefore rapidly degraded in a SUV3/PNPase-dependent manner |
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Download this section (compressed HTML)Q: How does Suv3 promote processing of polycistronic mitochondrial precursors without PNPase: by remodeling RNA for RNase P/RNase Z cleavage, or by surveillance of aberrant intermediates?
Experiment: Rescue Suv3 knockdown with helicase-dead (DExH motif) Suv3 and measure processing of tRNA junction precursors by junction-spanning RT-qPCR and northern blotting.
Hypothesis: Suv3 helicase activity is required for tRNA-junction processing in fly mitochondria.
Type: genetic rescue
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