2rvl
From Proteopedia
Solution structure of the chromodomain of HP1alpha with the N-terminal tail
Structural highlights
FunctionCBX5_MOUSE Component of heterochromatin that recognizes and binds histone H3 tails methylated at 'Lys-9' (H3K9me), leading to epigenetic repression. In contrast, it is excluded from chromatin when 'Tyr-41' of histone H3 is phosphorylated (H3Y41ph). Can interact with lamin-B receptor (LBR). This interaction can contribute to the association of the heterochromatin with the inner nuclear membrane. Involved in the formation of functional kinetochore through interaction with MIS12 complex proteins (By similarity). Publication Abstract from PubMedThe chromodomain of HP1alpha binds directly to lysine 9-methylated histone H3 (H3K9me). This interaction is enhanced by phosphorylation of serine residues in the N-terminal tail of HP1alpha by unknown mechanism. Here we show that phosphorylation modulates flexibility of HP1alpha's N-terminal tail, which strengthens the interaction with H3. NMR analysis of HP1alpha's chromodomain with N-terminal tail reveals that phosphorylation does not change the overall tertiary structure, but apparently reduces the tail dynamics. Small angle X-ray scattering confirms that phosphorylation contributes to extending HP1alpha's N-terminal tail. Systematic analysis using deletion mutants and replica exchange molecular dynamics simulations indicate that the phosphorylated serines and following acidic segment behave like an extended string and dynamically bind to H3 basic residues; without phosphorylation, the most N-terminal basic segment of HP1alpha inhibits interaction of the acidic segment with H3. Thus, the dynamic string-like behavior of HP1alpha's N-terminal tail underlies the enhancement in H3 binding due to phosphorylation. Extended string-like binding of the phosphorylated HP1alpha N-terminal tail to the lysine 9-methylated histone H3 tail.,Shimojo H, Kawaguchi A, Oda T, Hashiguchi N, Omori S, Moritsugu K, Kidera A, Hiragami-Hamada K, Nakayama J, Sato M, Nishimura Y Sci Rep. 2016 Mar 3;6:22527. doi: 10.1038/srep22527. PMID:26934956[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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