Prof Simon WAIN-HOBSON (Molecular Retrovirology Unit, Institut Pasteur, Paris, France) will give a seminar on October 7, 2011 entitled: "Novel human restriction enzymes for microbes – part of a much bigger picture".
Date: Friday, 7 October 2011
Time: 11:30 a.m. - 1:00 p.m.
Venue: Seminar Room 1, G/F, Laboratory Block, Faculty of Medicine Building 21 Sassoon Road, Pokfulam, Hong Kong
Bacteriophage targeted restriction enzymes resulted in DNA cleavage and helped usher in the DNA revolution. A new class of mammalian restriction enzymes, called APOBEC3 polynucleotide cytidine deaminases, have been identified that can edit single stranded retroviral DNA leading to DNA degradation downstream. Both HIV and HBV are vulnerable yet have solved the APOBEC3 problem in different ways. As DNA comes alive when single stranded it is no surprise that DNA viruses such as human herpesviruses being particularly vulnerable. That the APOBEC3 restriction enzymes were viral specific fitted nicely with the observation that several could be induced by type I and II interferons. Yet given that thermodynamics teaches us that no system is perfect, how does the host cell protect its mitochondrial and nuclear DNA from these enzymes? After all the bacterial genome is protected by a modification enzyme. Here the parallel breaks down. Human mitochondrial and nuclear DNA are edited; indeed some of the APOBEC3 enzymes are pro-apoptotic and appear to be part of an unsuspected DNA catabolic pathway. Every sample of peripheral blood that we have studied, whether they be infectious disease associated or normal controls show signs of APOBEC3 editing of human DNA. There is far more mutation that hitherto expected. It will be argued that cancer is a pathological downside to the evolution of the APOBEC3 locus.
Croucher-Pasteur Exchange Programme:
In collaboration with the International Affairs Department of Institut Pasteur and the Croucher Foundation, the Centre is establishing an exchange programme for students and post-doctoral fellows resident in Hong Kong in order to strengthen the scientific collaboration between Hong Kong and France. A 2 to 3 year scholarship covering travel, living and university registration expenses will be available for students and post-doctoral fellows resident in Hong Kong wishing to perform research work in laboratories of Institut Pasteur Paris. A lecture series of Pasteur scientists is organised to enable Hong Kong students to meet personally principal investigators from Institut Pasteur, know their scientific work and prospects of pursuing scientific work in their laboratories.