title: Histone H2A deubiquitinase activity of the Polycomb repressive complex PR-DUB.
abstract: Polycomb group (PcG) proteins are transcriptional repressors that control processes ranging from the maintenance of cell fate decisions and stem cell pluripotency in animals to the control of flowering time in plants. In Drosophila, genetic studies identified more than 15 different PcG proteins that are required to repress homeotic (HOX) and other developmental regulator genes in cells where they must stay inactive. Biochemical analyses established that these PcG proteins exist in distinct multiprotein complexes that bind to and modify chromatin of target genes. Among those, Polycomb repressive complex 1 (PRC1) and the related dRing-associated factors (dRAF) complex contain an E3 ligase activity for monoubiquitination of histone H2A (refs 1-4). Here we show that the uncharacterized Drosophila PcG gene calypso encodes the ubiquitin carboxy-terminal hydrolase BAP1. Biochemically purified Calypso exists in a complex with the PcG protein ASX, and this complex, named Polycomb repressive deubiquitinase (PR-DUB), is bound at PcG target genes in Drosophila. Reconstituted recombinant Drosophila and human PR-DUB complexes remove monoubiquitin from H2A but not from H2B in nucleosomes. Drosophila mutants lacking PR-DUB show a strong increase in the levels of monoubiquitinated H2A. A mutation that disrupts the catalytic activity of Calypso, or absence of the ASX subunit abolishes H2A deubiquitination in vitro and HOX gene repression in vivo. Polycomb gene silencing may thus entail a dynamic balance between H2A ubiquitination by PRC1 and dRAF, and H2A deubiquitination by PR-DUB.
authors.affiliation: European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany.
authors.forename: Johanna C
authors.initials: JC
authors.lastname: Scheuermann
authors.forename: Andrés Gaytán
authors.initials: AG
authors.lastname: de Ayala Alonso
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Oktaba
authors.forename: Nga
authors.initials: N
authors.lastname: Ly-Hartig
authors.forename: Robert K
authors.initials: RK
authors.lastname: McGinty
authors.forename: Sven
authors.initials: S
authors.lastname: Fraterman
authors.forename: Matthias
authors.initials: M
authors.lastname: Wilm
authors.forename: Tom W
authors.initials: TW
authors.lastname: Muir
authors.forename: Jürg
authors.initials: J
authors.lastname: Müller
mesh_terms: D000483:Alleles; D000818:Animals; D055162:Biocatalysis; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000196:embryology / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D020868:Gene Silencing; D005801:Genes, Homeobox / Q000235:genetics; D017344:Genes, Insect / Q000235:genetics; D005816:Genetic Complementation Test; D006657:Histones / Q000378:metabolism*; D006801:Humans; D046912:Multiprotein Complexes / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D009707:Nucleosomes / Q000737:chemistry / Q000378:metabolism; D063150:Polycomb Repressive Complex 1; D012097:Repressor Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D025801:Ubiquitin / Q000378:metabolism; D043222:Ubiquitin Thiolesterase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D054875:Ubiquitination / Q000502:physiology*
chemical_list: C111660:ASX protein, Drosophila; D029721:Drosophila Proteins; D006657:Histones; D046912:Multiprotein Complexes; D009707:Nucleosomes; C066770:Pc protein, Drosophila; D012097:Repressor Proteins; D025801:Ubiquitin; D063150:Polycomb Repressive Complex 1; D043222:Ubiquitin Thiolesterase