The domesticated transposase ALP2 mediates formation of a novel Polycomb protein complex by direct interaction with MSI1, a core subunit of Polycomb Repressive Complex 2 (PRC2)

by Christos N. Velanis, Pumi Perera, Bennett Thomson, Erica de Leau, Shih Chieh Liang, Ben Hartwig, Alex F örderer, Harry Thornton, Pedro Arede, Jiawen Chen, Kimberly M. Webb, Serin Gümüs, Geert De Jaeger, Clinton A. Page, C. Nathan Hancock, Christos Spanos, Juri Rappsilber, Philipp Voigt, Franziska Turck, Frank Wellmer, Justin Goodrich A large fraction of plant genomes is composed of transposable elements (TE), which provide a potential source of novel genes through “domestication”–the process whereby the proteins encoded by TE diverge in sequence, lose their ability to catalyse transposition and instead acquire novel func tions for their hosts. In Arabidopsis, ANTAGONIST OF LIKE HETEROCHROMATIN PROTEIN 1 (ALP1) arose by domestication of the nuclease component ofHarbinger class TE and acquired a new function as a component of POLYCOMB REPRESSIVE COMPLEX 2 (PRC2), a histone H3K27me3 methyltransferase involved in regulation of host genes and in some cases TE. It was not clear how ALP1 associated with PRC2, nor what the functional consequence was. Here, we identify ALP2 genetically as a suppressor of Polycomb-group (PcG) mutant phenotypes and show that it arose from the second, DNA binding component ofHarbinger transposases. Molecular analysis of PcG compromised backgrounds reveals thatALP genes oppose silencing and H3K27me3 deposition at key PcG target genes. Proteomic analysis reveals that ALP1 and ALP2 are components of a variant PRC2 complex that contains the four...
Source: PLoS Genetics - Category: Genetics & Stem Cells Authors: Source Type: research