A phosphatase complex that dephosphorylates gammaH2AX regulates DNA damage checkpoint recovery.
One of the earliest marks of a double-strand break (DSB) in eukaryotes is serine phosphorylation of the histone variant H2AX at the carboxy-terminal SQE motif to create gammaH2AX-containing nucleosomes. Budding-yeast histone H2A is phosphorylated in a similar manner by the checkpoint kinases Tel1 and Mec1 (ref. 2; orthologous to mammalian ATM and ATR, respectively) over a 50-kilobase region surrounding the DSB. This modification is important for recruiting numerous DSB-recognition and repair factors to the break site, including DNA damage checkpoint proteins, chromatin remodellers and cohesins. Multiple mechanisms for eliminating gammaH2AX as DNA repair completes are possible, including removal by histone exchange followed potentially by degradation, or, alternatively, dephosphorylation. Here we describe a three-protein complex (HTP-C, for histone H2A phosphatase complex) containing the phosphatase Pph3 that regulates the phosphorylation status of gammaH2AX in vivo and efficiently dephosphorylates gammaH2AX in vitro. gammaH2AX is lost from chromatin surrounding a DSB independently of the HTP-C, indicating that the phosphatase targets gammaH2AX after its displacement from DNA. The dephosphorylation of gammaH2AX by the HTP-C is necessary for efficient recovery from the DNA damage checkpoint.
Keogh
Michael-Christopher
MC
Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, USA.
Kim
Jung-Ae
JA
Downey
Michael
M
Fillingham
Jeffrey
J
Chowdhury
Dipanjan
D
Harrison
Jacob C
JC
Onishi
Megumi
M
Datta
Nira
N
Galicia
Sarah
S
Emili
Andrew
A
Lieberman
Judy
J
Shen
Xuetong
X
Buratowski
Stephen
S
Haber
James E
JE
Durocher
Daniel
D
Greenblatt
Jack F
JF
Krogan
Nevan J
NJ
D002453:Cell Cycle; D002843:Chromatin / Q000235:genetics / Q000378:metabolism; D004249:DNA Damage / Q000528:radiation effects; D004260:DNA Repair; D006657:Histones / Q000378:metabolism*; D046912:Multiprotein Complexes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D010749:Phosphoprotein Phosphatases / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*
D002843:Chromatin; D006657:Histones; D046912:Multiprotein Complexes; D029701:Saccharomyces cerevisiae Proteins; C507778:gammaH2AX protein, S cerevisiae; C502440:PPH3 protein, S cerevisiae; D010749:Phosphoprotein Phosphatases