5J8Y

Crystal structure of the Scm-SAM and Sfmbt-SAM heterodimer

Summary for 5J8Y

• Entry DOI: 10.2210/pdb5j8y/pdb
• Descriptor: Polycomb protein Scm, Polycomb protein Sfmbt (3 entities in total)
• Functional Keywords: prc1 phorc sam domain polycom response element, drosophila, signaling protein, nuclear protein
• Biological source: Drosophila melanogaster (Fruit fly); More
• Cellular location: Nucleus : Q9VHA0 Q9VK33
• Total number of polymer chains: 4
• Total formula weight: 38084.10

Authors

Frey, F.,Benda, C.,Mueller, J. (deposition date: 2016-04-08, release date: 2016-05-18, Last modification date: 2024-01-10)

Primary citation

Frey, F.,Sheahan, T.,Finkl, K.,Stoehr, G.,Mann, M.,Benda, C.,Muller, J.
Molecular basis of PRC1 targeting to Polycomb response elements by PhoRC.
Genes Dev., 30:1116-1127, 2016

PubMed Abstract: Polycomb group (PcG) protein complexes repress transcription by modifying target gene chromatin. In Drosophila, this repression requires association of PcG protein complexes with cis-regulatory Polycomb response elements (PREs), but the interactions permitting formation of these assemblies are poorly understood. We show that the Sfmbt subunit of the DNA-binding Pho-repressive complex (PhoRC) and the Scm subunit of the canonical Polycomb-repressive complex 1 (PRC1) directly bind each other through their SAM domains. The 1.9 Å crystal structure of the Scm-SAM:Sfmbt-SAM complex reveals the recognition mechanism and shows that Sfmbt-SAM lacks the polymerization capacity of the SAM domains of Scm and its PRC1 partner subunit, Ph. Functional analyses in Drosophila demonstrate that Sfmbt-SAM and Scm-SAM are essential for repression and that PhoRC DNA binding is critical to initiate PRC1 association with PREs. Together, this suggests that PRE-tethered Sfmbt-SAM nucleates PRC1 recruitment and that Scm-SAM/Ph-SAM-mediated polymerization then results in the formation of PRC1-compacted chromatin.

PubMed: 27151979
DOI: 10.1101/gad.279141.116

Experimental method

X-RAY DIFFRACTION (1.98 Å)