[Seminar] From X-ray of ADP-ribosylation to Cryo-EM of inflammasome

Seminar

Title: From X-ray of ADP-ribosylation to Cryo-EM of inflammasome

Speaker: Pietro Fontana

Affiliation: applicant for an EMBO fellowship

Host: Maria Arménia Carrondo

Abstract: 

ADP-ribosylation (ADPr) is a post-transnational modification (PTM) of proteins that controls many cellular processes, including DNA repair, and is carried out mainly by the enzyme PARP1. We recently discovered a novel factor involved in ADPr-dependent DNA repair, which we named Histone Parylation Factor 1 (HPF1). We found that HPF1 is a PARP1 binding protein which regulates PARP1 activity, allowing PARP1 to modify substrate proteins on serine residues (Ser-ADPr), a previously unreported PTM. The structure of HPF1 was solved by X-ray crystallography which allowed for continued structurally targeted studies to discover the mechanism of HPF1 influence on PARP1. Additionally, we performed a glycohydrolase screen and identified ARH3/ADPRHL2 as the only human glycohydrolase capable of efficiently and specifically removing Ser-ADPr. Finally, we demonstrated that Ser-ADPr is a conserved PTM, also present in the model organism Drosophila melanogaster, where it is removed by a different mechanism.

In 2019 Pietro will join the Wu Lab where he will work on Innate immunology of Inflammasome 1 (NLPR1). Inflammasomes are multiprotein complexes which recognize pathogen-associated molecular patterns (PAMPs) from pathogens, or danger-associated molecular patterns (DAMPs) from the host. Despite NLRP1's essential role in immunity and cancer, the mechanism of its activation and signalling remains elusive, especially at the molecular/structural level. For this purpose, he will adopt a multi-disciplinary approach based on structural and biochemical characterization, and dissect mechanistically the physiological function of the NLRP1 inflammasome.

He has been a Crystallographer so far, but is applying for a fellowship to work on cryoEM in Boston. His seminar will be on his PhD work but also in his project for the future, especially why doing cryoEM. So, a very similar situation to most of you.