Intrinsic nucleic acid-binding activity of Chp1 chromodomain is required for heterochromatic gene silencing.
Centromeric heterochromatin assembly in fission yeast requires the RNAi pathway. Chp1, a chromodomain (CD) protein, forms the Ago1-containing RNA-induced transcriptional silencing (RITS) complex and recruits siRNA-bound RITS to methylated histone H3 lysine 9 (H3K9me) via its CD. Here, we show that the CD of Chp1 (Chp1-CD) possesses unique nucleic acid-binding activities that are essential for heterochromatic gene silencing. Detailed electrophoretic-mobility shift analyses demonstrated that Chp1 binds to RNA via the CD in addition to its central RNA-recognition motif. Interestingly, robust RNA- and DNA-binding activity of Chp1-CD was strongly enhanced when it was bound to H3K9me, which was revealed to involve a positively charged domain within the Chp1-CD by structural analyses. These results demonstrate a role for the CD that provides a link between RNA, DNA, and methylated histone tails to ensure heterochromatic gene silencing.
Laboratory for Chromatin Dynamics, RIKEN Center for Developmental Biology, Kobe, Hyogo 650-0047, Japan.
Mayumi
M
Ishida
Hideaki
H
Shimojo
Aki
A
Hayashi
Rika
R
Kawaguchi
Yasuko
Y
Ohtani
Koichi
K
Uegaki
Yoshifumi
Y
Nishimura
Jun-Ichi
J
Nakayama
D000595:Amino Acid Sequence; D060565:Argonaute Proteins / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000235:genetics*; D047369:Chromatin Immunoprecipitation; D004247:DNA / Q000737:chemistry; D004305:Dose-Response Relationship, Drug; D039642:Eukaryotic Initiation Factors / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal; D020868:Gene Silencing; D006570:Heterochromatin / Q000737:chemistry*; D007700:Kinetics; D008745:Methylation; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D012313:RNA / Q000737:chemistry; D012568:Schizosaccharomyces / Q000378:metabolism*; D029702:Schizosaccharomyces pombe Proteins / Q000235:genetics*; D017386:Sequence Homology, Amino Acid
C115848:AGO1 protein, human; D060565:Argonaute Proteins; D018797:Cell Cycle Proteins; C115018:Chp1 protein, S pombe; D039642:Eukaryotic Initiation Factors; D006570:Heterochromatin; D029702:Schizosaccharomyces pombe Proteins; D012313:RNA; D004247:DNA