The Structure and Cell Biology of Bacteriophage Tubulins

In collaboration with Joe Pogliano (UCSD) we have discovered a family of tubulins encoded by very large bacteriophage (~300Kb), and have determined the crystal structure of the first phage cytoskeletal element - a tubulin family member known as PhuZ. While longitudinal interactions are well conserved in all tubulins, the crystal structure which mimics longitudinal packing in the filaments, revealed a gap between molecules. Instead, filaments are formed by a novel C-terminal extension that directly links molecules in the filament. In vivo observations of infected cells reveals that PhuZ forms a spindle-like structure that position phage particles at the cell midline. Altering PhuZ dynamics leads to phage mispositioning and a significantly decreased burst size. In a continued collaboration, we now focus on understanding the cell and structural biology underlying this remarkable observation.