Philip Johnson

Here a CRISPR, There a CRISPR: Why Not Everywhere a CRISPR?

Abstract

Just like humans, bacteria and archaea must constantly fend off viral infections. Microbes have developed many anti-viral defense mechanisms, the most fascinating of which is CRISPR-Cas, which serves as a remarkably effective adaptive immune system. While humans have recently hijacked this system for use in precision genome editing, it evolved naturally as a means for microbes to remember past viral pathogens and to defend themselves against future infections by precisely chopping up remembered viral genomes. Despite CRISPR-Cas being found scattered throughout the tree of life (in >40% of sequenced bacteria and archaea) as well as providing near-perfect protection from infection given a matching viral memory, viruses continue to exist and many species of microbes consistently lack a CRISPR-Cas system. I will explore these puzzles and propose hypotheses to explain coexistence and the ecological-evolutionary patterns of CRISPR-Cas incidence.

About the Speaker

Philip Johnson is an assistant professor in the Department of Biology at the University of Maryland. He studied biology and computer science to earn his A.B. from Harvard University. Johnson then worked at the National Center for Biotechnology Information for three years before starting his graduate studies in biophysics with a focus on computational biology and population genetics at the University of California, Berkeley. His Ph.D. was followed by a postdoc at Emory University where he brought population genetic approaches to modeling immune system dynamics.