Abstract
The trimethylation of histone H3 on lysine 9 (H3K9me3) – a mark recognized by HP1 that depends on the Suv39h lysine methyltransferases (KMTs) – has provided a basis for the reader/writer model to explain HP1 accumulation at pericentric heterochromatin in mammals. Here, we identify the Suv39h1 paralog, as a unique enhancer of HP1α sumoylation both in vitro and in vivo. The region responsible for promoting HP1α sumoylation (aa1–167) is distinct from the KMT catalytic domain and mediates binding to Ubc9. Tethering the 1–167 domain of Suv39h1 to pericentric heterochromatin, but not mutants unable to bind Ubc9, accelerates the de novo targeting of HP1α to these domains. Our results establish an unexpected feature of Suv39h1, distinct from the KMT activity, with a major role for heterochromatin formation. We discuss how linking Suv39h1 to the SUMO pathway provides conceptual implications for our general view on nuclear domain organization and physiological functions.
Highlights
To cite this version: Christèle Maison, Delphine Bailly, Jean-Pierre Quivy, Geneviève Almouzni
The trimethylation of histone H3 on lysine 9 (H3K9me3) – a mark recognized by HP1 that depends on the Suv39h lysine methyltransferases (KMTs) – has provided a basis for the reader/writer model to explain HP1 accumulation at pericentric heterochromatin in mammals
We recently found that in the absence of Suv39h-dependent H3K9me[3], HP1a sumoylation could promote its de novo targeting to pericentric heterochromatin in mammalian cells[16]
Summary
To cite this version: Christèle Maison, Delphine Bailly, Jean-Pierre Quivy, Geneviève Almouzni. The methyltransferase Suv39h1 links the SUMO pathway to HP1a marking at pericentric heterochromatin. The trimethylation of histone H3 on lysine 9 (H3K9me3) – a mark recognized by HP1 that depends on the Suv39h lysine methyltransferases (KMTs) – has provided a basis for the reader/writer model to explain HP1 accumulation at pericentric heterochromatin in mammals. We proposed at least two distinct steps in heterochromatin formation: first ‘seeding’ requiring HP1 sumoylation, and second amplification and propagation exploiting H3K9me[3] The importance in this scheme of a SUMO-dependent step raises the issue of the identification of the SUMO E3 ligase specific for HP1a at pericentric domains. Our results unveil an unanticipated function for Suv39h1 that provides a missing link between the SUMO pathway and HP1a marking at pericentric heterochromatin
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