External Serine ADP-ribosylation signaling Seminar details March 19, 2019, 12:00 am @ MSI SLTDr Ivan Matic Host: Ron Hay ADP-ribosylation (ADPr) is a key player in many physiological and disease conditions, best known for its role in the maintenance of genome stability. Despite the biological and clinical importance of ADPr little is known about the functional consequences of site-specific ADPr. With a first truly unbiased and unambiguous mapping of ADPr sites, we uncovered Serine ADPr as a new type of histone mark that responds to DNA damage. Shortly afterwards we described the molecular basis of Ser-ADPr by showing that HPF1 changes PARP1 specificity toward serine. More recently we showed that Ser-ADPr is the primary residue for ADPr upon DNA damage and revealed an intriguing interplay of canonical histone marks, such as lysine acetylation and phosphorylation, with Ser-ADPr.