Phosphorylated intrinsically disordered region of FACT masks its nucleosomal DNA binding elements.
FACT is a heterodimer of SPT16 and SSRP1, which each contain several conserved regions in the primary structure. The interaction of FACT with nucleosomes induces chromatin remodeling through the combinatorial action of its distinct functional protein regions. However, there is little mechanistic insight into how these regions cooperatively contribute to FACT functions, particularly regarding the recognition of nucleosomal DNA. Here, we report the identification of novel phosphorylation sites of Drosophila melanogaster FACT (dFACT) expressed in Sf9 cells. These sites are densely concentrated in the acidic intrinsically disordered (ID) region of the SSRP1 subunit and control nucleosomal DNA binding by dFACT. This region and the adjacent segment of the HMG domain form weak electrostatic intramolecular interactions, which is reinforced by the phosphorylation, thereby blocking DNA binding competitively. Importantly, this control mechanism appears to support rapid chromatin transactions during early embryogenesis through the dephosphorylation of some sites in the maternally transmitted dSSRP1.
Tsunaka
Yasuo
Y
Takara-Bio Endowed Laboratory, Institute for Protein Research, Osaka University, Suita, Osaka 565-0874, Japan.
Toga
Junko
J
Yamaguchi
Hiroto
H
Tate
Shin-ichi
S
Hirose
Susumu
S
Morikawa
Kosuke
K
D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D042002:Chromatin Assembly and Disassembly / Q000502:physiology*; D004247:DNA / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster; D004625:Embryo, Nonmammalian / Q000378:metabolism; D047108:Embryonic Development / Q000502:physiology; D006609:High Mobility Group Proteins / Q000235:genetics / Q000378:metabolism*; D009707:Nucleosomes / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation / Q000502:physiology; D017434:Protein Structure, Tertiary / Q000502:physiology; D035602:Transcriptional Elongation Factors / Q000235:genetics / Q000378:metabolism*
D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; C518656:FACT protein, Drosophila; D006609:High Mobility Group Proteins; D009707:Nucleosomes; C489543:SSRP protein, Drosophila; D035602:Transcriptional Elongation Factors; D004247:DNA