Dissection of affinity captured LINE-1 macromolecular complexes
- Massachusetts General Hospital, United States
- Moscow Institute of Physics and Technology, Russian Federation
- The Rockefeller University, United States
- NYU Langone Medical Center, United States
- Johns Hopkins University School of Medicine, United States
- Novosibirsk State University, Russian Federation
Abstract
Long Interspersed Nuclear Element-1 (LINE-1, L1) is a mobile genetic element active in human genomes. L1-encoded ORF1 and ORF2 proteins bind L1 RNAs, forming ribonucleoproteins (RNPs). These RNPs interact with diverse host proteins, some repressive and others required for the L1 lifecycle. Using differential affinity purifications, quantitative mass spectrometry, and next generation RNA sequencing, we have characterized the proteins and nucleic acids associated with distinctive, enzymatically active L1 macromolecular complexes. Among them, we describe a cytoplasmic intermediate that we hypothesize to be the canonical ORF1p/ORF2p/L1-RNA-containing RNP, and we describe a nuclear population containing ORF2p, but lacking ORF1p, which likely contains host factors participating in target-primed reverse transcription.
Data availability
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RNA-seq FASTAQ filesPublicly available at ProteomeXchange (accession no: PXD008542).
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RNAs associated with affinity captured LINE-1 ribonucleoproteinsPublicly available at the NCBI Gene Expression Omnibus (accession no: GSE108270).
Article and author information
Author details
Funding
National Institutes of Health (P41GM109824)
- Michael P Rout
National Institutes of Health (P41GM103314)
- Brian T Chait
National Institutes of Health (P50GM107632)
- Jef D Boeke
National Institutes of Health (R01GM654321)
- Jef D Boeke
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2018, Taylor et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Dissection of affinity captured LINE-1 macromolecular complexes
eLife 7:e30094.
https://doi.org/10.7554/eLife.30094
Further reading
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- Cell Biology
- Genetics and Genomics
The mechanisms by which a retrotransposon called LINE-1 duplicates itself and spreads through the human genome are becoming clearer.
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- Biochemistry and Chemical Biology
- Cancer Biology
Many cells in high glucose repress mitochondrial respiration, as observed in the Crabtree and Warburg effects. Our understanding of biochemical constraints for mitochondrial activation is limited. Using a Saccharomyces cerevisiae screen, we identified the conserved deubiquitinase Ubp3 (Usp10), as necessary for mitochondrial repression. Ubp3 mutants have increased mitochondrial activity despite abundant glucose, along with decreased glycolytic enzymes, and a rewired glucose metabolic network with increased trehalose production. Utilizing ∆ubp3 cells, along with orthogonal approaches, we establish that the high glycolytic flux in glucose continuously consumes free Pi. This restricts mitochondrial access to inorganic phosphate (Pi), and prevents mitochondrial activation. Contrastingly, rewired glucose metabolism with enhanced trehalose production and reduced GAPDH (as in ∆ubp3 cells) restores Pi. This collectively results in increased mitochondrial Pi and derepression, while restricting mitochondrial Pi transport prevents activation. We therefore suggest that glycolytic flux-dependent intracellular Pi budgeting is a key constraint for mitochondrial repression.
