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.
RNA-seq FASTAQ filesPublicly available at ProteomeXchange (accession no: PXD008542).
RNAs associated with affinity captured LINE-1 ribonucleoproteinsPublicly available at the NCBI Gene Expression Omnibus (accession no: GSE108270).
- Michael P Rout
- Brian T Chait
- Jef D Boeke
- John LaCava
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
- Stephen P Goff, Howard Hughes Medical Institute, Columbia University, United States
- Received: July 1, 2017
- Accepted: December 18, 2017
- Accepted Manuscript published: January 8, 2018 (version 1)
- Accepted Manuscript updated: January 10, 2018 (version 2)
- Version of Record published: February 21, 2018 (version 3)
- Version of Record updated: May 15, 2018 (version 4)
- Version of Record updated: September 11, 2018 (version 5)
- Version of Record updated: January 8, 2019 (version 6)
© 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.
The mechanisms by which a retrotransposon called LINE-1 duplicates itself and spreads through the human genome are becoming clearer.
Doublecortin (DCX) is a microtubule (MT)-associated protein that regulates MT structure and function during neuronal development and mutations in DCX lead to a spectrum of neurological disorders. The structural properties of MT-bound DCX that explain these disorders are incompletely determined. Here, we describe the molecular architecture of the DCX–MT complex through an integrative modeling approach that combines data from X-ray crystallography, cryo-electron microscopy, and a high-fidelity chemical crosslinking method. We demonstrate that DCX interacts with MTs through its N-terminal domain and induces a lattice-dependent self-association involving the C-terminal structured domain and its disordered tail, in a conformation that favors an open, domain-swapped state. The networked state can accommodate multiple different attachment points on the MT lattice, all of which orient the C-terminal tails away from the lattice. As numerous disease mutations cluster in the C-terminus, and regulatory phosphorylations cluster in its tail, our study shows that lattice-driven self-assembly is an important property of DCX.