EXPANDING THE GENETIC CODE AND STUDYING CYTOKINESIS REGULATORY SIN PATHWAY IN S.POMBRE

Abstract

Cytokinesis is the final event of cell cycle and is accomplished by the constriction of an actomyosin ring in many eukaryotes. In the fission yeast Schizosaccharomyces pombe, actomyosin ring constriction and cell wall formation are coordinated with the activity of a GTPase-driven signaling pathway termed the SIN. In the first part of this thesis, I characterized a new protein, Csc1p, and identified SIN-Inhibitory PP2A-complex, which is crucial for promoting Byr4p, a component of the GTPase-activating subunit, to re-localize to the SPB in late anaphase. For novel insights into cytokinesis in fission yeast, in the second part of this thesis, I developed a new method to study molecular interactions between essential proteins. I expanded the genetic code of S.pombe with photo-crosslinking amino acid azidophenylalanine (AzF). I engineered S.pombe cells with a translation system orthogonal to the E. coli tyrosyltRNA synthetase / tRNA and successfully incorporated AzF into endogenous proteins. In addition, proteins incorporated with AzF displayed the ability to form covalent cross-links. These tools should be of great use to further understand the process of cytokinesis and in exploring fission yeast cell biology, in general.