Histone lysine ribosylation

Histone proteins often undergo ribosylation (ar) i.e. the addition of poly (ADP-ribose) units specifically at the lysine residues. This modification is mediated by Poly [ADP-ribose] polymerase (PARP) enzymes. In this case, the NAD+ acts as the ADP-ribose donor. These are big units and each ADP-ribose moiety adds ~560 Da to the histone protein. ADP-ribosylation causes disruption of the nucleosome structure by loss of histone-DNA interaction on account of charge modification.

ADP ribosylation plays an important role in DNA break repair mechanisms.

Download table as Excel
Sites of histone lysine ribosylation
Site of modification Writers Erasers
H2AK13ar Poly [ADP-ribose] polymerase 1
H2BK30ar Poly [ADP-ribose] polymerase 1
H3K27ar Poly [ADP-ribose] polymerase 1
H3K37ar Poly [ADP-ribose] polymerase 1
H4K16ar Poly [ADP-ribose] polymerase 1