Polycomb group targeting through different binding partners of RING1B C-terminal domain.
RING1B, a Polycomb Group (PcG) protein, binds methylated chromatin through its association with another PcG protein called Polycomb (Pc). However, RING1B can associate with nonmethylated chromatin suggesting an alternate mechanism for RING1B interaction with chromatin. Here, we demonstrate that two proteins with little sequence identity between them, the Pc cbox domain and RYBP, bind the same surface on the C-terminal domain of RING1B (C-RING1B). Pc cbox and RYBP each fold into a nearly identical, intermolecular beta sheet with C-RING1B and a loop structure which are completely different in the two proteins. Both the beta sheet and loop are required for stable binding and transcription repression. Further, a mutation engineered to disrupt binding on the Drosophila dRING1 protein prevents chromatin association and PcG function in vivo. These results suggest that PcG targeting to different chromatin locations relies, in part, on binding partners of C-RING1B that are diverse in sequence and structure.
Wang
Renjing
R
Department of Biochemistry, University of Texas Health Science Center at San Antonio, MSC 7760, 7703 Floyd Curl Drive, San Antonio, TX 78229-3990, USA.
Taylor
Alexander B
AB
Leal
Belinda Z
BZ
Chadwell
Linda V
LV
Ilangovan
Udayar
U
Robinson
Angela K
AK
Schirf
Virgil
V
Hart
P John
PJ
Lafer
Eileen M
EM
Demeler
Borries
B
Hinck
Andrew P
AP
McEwen
Donald G
DG
Kim
Chongwoo A
CA
D000595:Amino Acid Sequence; D000818:Animals; D030801:Animals, Genetically Modified; D002843:Chromatin / Q000378:metabolism; D018360:Crystallography, X-Ray; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000378:metabolism*; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000235:genetics; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D019906:Nuclear Magnetic Resonance, Biomolecular; D063150:Polycomb Repressive Complex 1; D063146:Polycomb-Group Proteins; D011485:Protein Binding; D017434:Protein Structure, Tertiary / Q000235:genetics; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism*; D012097:Repressor Proteins / Q000737:chemistry / Q000378:metabolism*; D016415:Sequence Alignment; D044767:Ubiquitin-Protein Ligases / Q000737:chemistry* / Q000378:metabolism*; D014461:Ultracentrifugation
D002843:Chromatin; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D047908:Intracellular Signaling Peptides and Proteins; D063146:Polycomb-Group Proteins; C434957:RYBP protein, human; D011994:Recombinant Proteins; D012097:Repressor Proteins; D063150:Polycomb Repressive Complex 1; C489841:RNF2 protein, human; C570575:Sce protein, Drosophila; D044767:Ubiquitin-Protein Ligases