Dual recognition of phosphoserine and phosphotyrosine in histone variant H2A.X by DNA damage response protein MCPH1

Abstract

Tyr142, the C-terminal amino acid of histone variant H2A.X is phosphorylated by WSTF (Williams-Beuren syndrome transcription factor), a component of the WICH complex (WSTF-ISWI chromatin-remodeling complex), under basal conditions in the cell. In response to DNA double-strand breaks (DSBs), H2A.X is instantaneously phosphorylated at Ser139 by the kinases ATM and ATR and is progressively dephosphorylated at Tyr142 by the Eya1 and Eya3 tyrosine phosphatases, resulting in a temporal switch from a postulated diphosphorylated (pSer139, pTyr142) to monophosphorylated (pSer139) H2A.X state. How mediator proteins interpret these two signals remains a question of fundamental interest. We provide structural, biochemical, and cellular evidence that Microcephalin (MCPH1), an early DNA damage response protein, can read both modifications via its tandem BRCA1 C-terminal (BRCT) domains, thereby emerging as a versatile sensor of H2A.X phosphorylation marks. We show that MCPH1 recruitment to sites of DNA damage is linked to both states of H2A.X.

Protein and DNA Modifications: Evolutionary Imprints of Bacterial Biochemical Diversification and Geochemistry on the Provenance of Eukaryotic Epigenetics

“…Among readers of phosphate marks the conserved 14-3-3 module comprised of a-a repeats, the all-b FHA, SJA/ FYR, and BRCT domain (both with a/b folds) (Fig. 2J) are traceable to the LECA (Lloyd et al 2009;Zippo et al 2009;Garcia-Alai et al 2010;Singh et al 2012). However, the histone H3T3-binding BIR domain appears to be a later innovation in eukaryotic evolution, probably emerging concomitantly with haspin-like kinases that modify the position recognized by them (Jeyaprakash et al 2011).…”

Histone Recognition by Tandem Modules and Modulation by Multiple PTMs

“…Structural and functional studies revealed that a DNA damage response protein MCPH1 could recognize such a diphosphorylation pattern of H2AX "S139ph-Y142ph" (K D = 4.4 μM) through engagement of its tandem BRCT domain (Fig. 7.3a) (Singh et al 2012). By contrast, another tandem BRCTcontaining protein, MDC1, is unable to recognize such a pattern though it binds H2AX S139ph at micromolar affinity (K D = 2.2 μM).…”

Chemical “Diversity” of Chromatin Through Histone Variants and Histone Modifications

“…This residue is ubiquitously phosphorylated and its dephosphorylation is associated with DNA damage repair [101,102]. A recent study showed that MCPH1, a protein associated with DNA damage response, interacts with di-phosphorylated (S139/Y142ph) H2A.X [103]. Finally, recent data showed that H2A.X S16 can also be phosphorylated, and this modification results in decreased H2A.X ubiquitylation and cell transformation [104].…”