A novel ubiquitin mark at the N-terminal tail of histone H2As targeted by RNF168 ubiquitin ligase.
Ubiquitination of histones plays a critical role in the regulation of several processes within the nucleus, including maintenance of genome stability and transcriptional regulation. The only known ubiquitination site on histones is represented by a conserved Lys residue located at the C terminus of the protein. Here, we describe a novel ubiquitin mark at the N-terminal tail of histone H2As consisting of two Lys residues at positions 13 and 15 (K13/K15). This "bidentate" site is a target of the DNA damage response (DDR) ubiquitin ligases RNF8 and RNF168. Histone mutants lacking the K13/K15 site impair RNF168- and DNA damage-dependent ubiquitination. Conversely, inactivation of the canonical C-terminal site prevents the constitutive monoubiquitination of histone H2As but does not abolish the ubiquitination induced by RNF168. A ubiquitination-defective mutant is obtained by inactivating both the N- and the C-terminal sites, suggesting that these are unique, non-redundant acceptors of ubiquitination on histone H2As. This unprecedented result implies that RNF168 generates a qualitatively different Ub mark on chromatin.
Department of Pharmaceutical Sciences, University of Piemonte Orientale "A. Avogadro", Novara, Italy.
Marco
M
Gatti
Sabrina
S
Pinato
Elena
E
Maspero
Paolo
P
Soffientini
Simona
S
Polo
Lorenza
L
Penengo
D000595:Amino Acid Sequence; D042002:Chromatin Assembly and Disassembly; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000378:metabolism; D057809:HEK293 Cells; D006657:Histones / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D017434:Protein Structure, Tertiary; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism*; D054875:Ubiquitination
D004268:DNA-Binding Proteins; C468783:H2AX protein, human; D006657:Histones; C486521:RNF8 protein, human; C535210:RNF168 protein, human; D044767:Ubiquitin-Protein Ligases