Affinity proteomics reveals human host factors implicated in discrete stages of LINE-1 retrotransposition

Martin S. Taylor, John LaCava, Paolo Mita, Kelly R. Molloy, Cheng Ran Lisa Huang, Donghui Li, Emily M. Adney, Hua Jiang, Kathleen H. Burns, Brian T. Chait, Michael P. Rout, Jef D. Boeke, Lixin Dai

Research output: Contribution to journalArticlepeer-review


LINE-1s are active human DNA parasites that are agents of genome dynamics in evolution and disease. These streamlined elements require host factors to complete their life cycles, whereas hosts have developed mechanisms to combat retrotransposition's mutagenic effects. As such, endogenous L1 expression levels are extremely low, creating a roadblock for detailed interactomic analyses. Here, we describe a system to express and purify highly active L1 RNP complexes from human suspension cell culture and characterize the copurified proteome, identifying 37 high-confidence candidate interactors. These data sets include known interactors PABPC1 and MOV10 and, with in-cell imaging studies, suggest existence of at least three types of compositionally and functionally distinct L1 RNPs. Among the findings, UPF1, a key nonsense-mediated decay factor, and PCNA, the polymerase-delta-associated sliding DNA clamp, were identified and validated. PCNA interacts with ORF2p via a PIP box motif; mechanistic studies suggest that this occurs during or immediately after target-primed reverse transcription.

Original languageEnglish (US)
Pages (from-to)1034-1048
Number of pages15
Issue number5
StatePublished - Nov 21 2013

ASJC Scopus subject areas

  • General Biochemistry, Genetics and Molecular Biology


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