John Cannon, PhD

Photo of John Cannon, PhD

Molecular Microbiology and Immunology

Associate Professor
Director and Chair Genetics Area Program

573-882-2780

Profile

Faithful transmission of the genome to progeny cells is a fundamental process required by all organisms. Errors in this process cause several common human diseases like Downs syndrome and cancer. The machinery that controls the eukaryotic cell cycle is very evolutionarily conserved. We study the control of the cell cycle by protein phosphatase-1 in the single-celled, eukaryote Saccharomyces cerevisiae, or budding yeast. Although this organism has been used for millennia for baking and brewing, we exploit its powerful molecular genetic tools to unravel how the machinery of cell division is regulated. The Glc7, protein phosphatase-1 associates with several noncatalytic regulatory subunits. The holoenzyme formed with Sds22 resides in the nucleus and is responsible for dephosphorylating proteins required for the metaphase to anaphase transition. Our genetic analysis revealed that Glc8 activates and Frp3 inhibits the activity of Glc7. Both Glc8 and Fpr3 modulate Glc7 activity by affecting Glc7 conformation like chaperones. Indeed, Fpr3 is a protein proline isomerase. Glc8 only functions when it is phosphorylated. We found that Glc8 is phosphorylated by cyclin-dependent protein kinase, Pho85. Glc8 kinase primarily stems from two of the ten Pho85 cyclins, Pcl6 and Pcl7. These cyclins appear to maximize their levels in S-phase. Therefore, the pathway that activates Glc7 by Glc8 is throttled on in S-phase, just prior to the requirement for Glc7 in metaphase. We are currently exploring the inputs to the Pcl6 and Pcl7 regulation to understand how the cell exploits this regulatory network. All these yeast proteins are conserved in humans. Therefore, we imagine that much of our findings will illustrate how the cell cycle is regulated in larger eukaryotic organisms.

Academic Information

Associate Professor
Director and Chair Genetics Area Program

Office

M604B Medical Sciences Bldg.
Columbia, MO 65212
United States

P. 573-882-2780

Research Interests

  • Genetics of Saccharomyces cerevisiae
  • Role of protein phosphatase in cell cycle regulation

Areas of Expertise

  • Cancer Biology
  • Cell Biology
  • Genetics
  • Signal Transduction

Education & Training

Post-Graduate School

1983, PhD, University of Wisconsin-Madison

Publications