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Topology and enzymatic properties of a canonical Polycomb repressive complex 1 isoform
Author(s) -
Colombo Matteo,
Pessey Ombeline,
Marcia Marco
Publication year - 2019
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1002/1873-3468.13442
Subject(s) - gene isoform , protein subunit , histone , ring (chemistry) , histone h3 , chemistry , enzyme , subcellular localization , topology (electrical circuits) , microbiology and biotechnology , biochemistry , gene , biology , stereochemistry , mathematics , organic chemistry , combinatorics
Polycomb repressive complex 1 ( PRC 1) catalyses monoubiquitination of histone H2A on Lys119, promoting gene silencing. Cells at different developmental stages and in different tissues express different PRC 1 isoforms. The topology, subunit composition, structural architecture and molecular mechanism of most of these isoforms are still poorly characterized. Here, we have purified a PRC 1 isoform comprising subunits RING 1B, PCGF 2, CBX 2 and PHC 2, two stable subcomplexes ( RING 1B‐ PCGF 2 and RING 1B‐ PHC 2) and the catalytic subunit RING 1B in isolation. By crosslinking mass spectrometry, we identified novel interactions between RING 1B and the three non‐catalytic subunits. Biochemical, biophysical, and enzymatic data suggest that CBX 2 and PHC 2 play a structural role, whereas PCGF 2 also modulates catalysis. Our data offer insights into the molecular architecture of PRC 1 and its histone ubiquitination activity.