8 Cell Cycle Control in Fission Yeast

Abstract

I. INTRODUCTION
A. Overview
The fission yeast Schizosaccharomyces pombe has proved to be a good model system for analysis of the eukaryotic cell cycle. A number of the key cell cycle regulatory molecules now being extensively studied in higher eukaryotes were first identified and characterized in fission yeast, and it has become clear that many of the regulatory networks elucidated through genetic analysis in S. pombe are conserved in higher eukaryotes as well (Nurse 1990). In this chapter, we consider the regulatory mechanisms that control progression through the mitotic cycle of fission yeast with particular emphasis on those mechanisms that ensure the correct timing and temporal ordering of key cell cycle transitions. However, we do not deal with the control of cytokinesis, which is discussed elsewhere in this volume (Su and Yanagida, this volume). We also consider what is known of the enzymology of DNA replication in fission yeast, whereas the accompanying chapters focus on the processes of mitosis and cytokinesis (Su and Yanagida, this volume) and of conjugation, meiosis, and sporulation (Yamamoto et al., this volume). We begin with a brief introduction to S. pombe and its life cycle.

B. Life Cycle and Genetics
S. pombe is a unicellular ascomycete fungus only distantly related to the budding yeast Saccharomyces cerevisiae (for discussion of phylogenetic relationships, see Sipiczki 1995). Fission yeast cells are rod-shaped, grow by apical extension, and divide by medial fission. The cells are usually haploid, with a haploid genome size similar to that of budding yeast at...