CANCELLED - Bacteriophage-encoded nucleus-like structures protect DNA from CRISPR

Friday, March 6, 2020 10:00 am - 10:00 am EST (GMT -05:00)


Presented by:

Joseph Bondy-Denomy
Joseph Bondy-Denomy, PhD
Assistant Professor
University of California, San Francisco
Dept. of Microbiology & Immunology

Membrane bound organelles are a central tenant of eukaryotic cell biology, and largely absent from prokaryotes. However, protein-encased structures have been identified in bacteria, for example encapsulins and carboxysomes that localize enzymes, but none that compartmentalize nucleic acid. However, recent work has described the discovery of a prokaryotic proteinaceous compartment that mirrors a nucleus, localizing DNA replication and transcription into a centrally located, segregated structure, while translation happens in the cytoplasm. Intriguingly, this structure is made inside a bacterium, but not by the bacterium. This process is entirely directed by a bacterial virus, or bacteriophage. I will discuss this remarkable structure and our recent findings that this proteinaceous nucleus-like compartment segregates phage DNA from restriction and CRISPR-Cas nucleases, providing the most broad spectrum resistance to bacterial immune pathways described to date. This will be contrasted with specific inhibitors of CRISPR-Cas function, or “anti-CRISPR” proteins, also encoded by phage that our group has identified.

stained cells