GAB-GFP BASED SYNTHETIC STUDIES ON CYTOKINESIS AND MITOTIC ENTRY REGULATION IN FISSION YEAST

Abstract

Understanding the spatial and temporal regulation of proteins is one of the key challenges in unraveling complex cellular processes in cell biology. By establishing a protein targeting strategy based on the Gab-GFP binding affinity, we gained new information in understanding two essential regulations during the fission yeast cell cycle, i.e., mitotic entry and cytokinesis. We first confirmed that fission yeast cells sense their size through a kinase protein Cdr2p and integrate this information with G2-phase / M-phase transition. In a parallel study, we synthetically rewired medial cell division in cells lacking Mid1p, a protein thought to be key to symmetric division in fission yeast. By targeting Rng2p, Cdc12p or Myo2p to the medial cortex, we bypassed the requirement for Mid1p in organizing cytokinetic nodes for actomyosin ring assembly. We also found that the order of assembly of ring proteins at the division site is not essential for medial cell division, and that Mid1p plays multiple roles pertaining to cytokinesis.