The preRC protein ORCA organizes heterochromatin by assembling histone H3 lysine 9 methyltransferases on chromatin.
Heterochromatic domains are enriched with repressive histone marks, including histone H3 lysine 9 methylation, written by lysine methyltransferases (KMTs). The pre-replication complex protein, origin recognition complex-associated (ORCA/LRWD1), preferentially localizes to heterochromatic regions in post-replicated cells. Its role in heterochromatin organization remained elusive. ORCA recognizes methylated H3K9 marks and interacts with repressive KMTs, including G9a/GLP and Suv39H1 in a chromatin context-dependent manner. Single-molecule pull-down assays demonstrate that ORCA-ORC (Origin Recognition Complex) and multiple H3K9 KMTs exist in a single complex and that ORCA stabilizes H3K9 KMT complex. Cells lacking ORCA show alterations in chromatin architecture, with significantly reduced H3K9 di- and tri-methylation at specific chromatin sites. Changes in heterochromatin structure due to loss of ORCA affect replication timing, preferentially at the late-replicating regions. We demonstrate that ORCA acts as a scaffold for the establishment of H3K9 KMT complex and its association and activity at specific chromatin sites is crucial for the organization of heterochromatin structure.
Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Champaign, United States.
Sumanprava
S
Giri
Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, Champaign, United States.
Vasudha
V
Aggarwal
Université Paris Diderot, Sorbonne Paris Cité, Laboratoire Epigénétique et Destin Cellulaire, UMR7216, Centre National de la Recherche Scientifique, Paris, France.
Julien
J
Pontis
Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Champaign, United States.
Zhen
Z
Shen
Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Champaign, United States.
Arindam
A
Chakraborty
Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Champaign, United States.
Abid
A
Khan
Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Champaign, United States.
Craig
C
Mizzen
Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Champaign, United States.
Kannanganattu V
KV
Prasanth
Université Paris Diderot, Sorbonne Paris Cité, Laboratoire Epigénétique et Destin Cellulaire, UMR7216, Centre National de la Recherche Scientifique, Paris, France.
Slimane
S
Ait-Si-Ali
Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, Champaign, United States.
Taekjip
T
Ha
Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Champaign, United States.
Supriya G
SG
Prasanth
D048868:Adaptor Proteins, Signal Transducing / Q000737:chemistry / Q000378:metabolism*; D002460:Cell Line; D006570:Heterochromatin / Q000378:metabolism*; D011495:Histone-Lysine N-Methyltransferase / Q000737:chemistry / Q000378:metabolism*; D006657:Histones / Q000378:metabolism; D006801:Humans; D008745:Methylation; D011499:Protein Processing, Post-Translational / Q000235:genetics; D000071456:Sequestosome-1 Protein
D048868:Adaptor Proteins, Signal Transducing; D006570:Heterochromatin; D006657:Histones; C099718:SQSTM1 protein, human; D000071456:Sequestosome-1 Protein; D011495:Histone-Lysine N-Methyltransferase
ORCA/LRWD1; cell biology; chromosomes; genes; heterochromatin; human; lysine methyl transferase; replication; single-molecule pull down