The Dynamics of Chromosome Replication in Yeast

Abstract

This chapter deals with the dynamic aspects of chromosome replication in yeast and describes how the program of replication is laid down and carried out in Saccharomyces cerevisiae, with particular emphasis on the dynamic aspects of. It explains how the control of replication initiation is tied to phases of the cell cycle, how the activation of different origins within the genome are coordinated, and how checkpoint surveillance systems monitor and ensure the orderly progress and completion of S phase. The chapter provides a brief overview of the methods that are used most commonly in studying replication––namely, (1) the autonomously replicating sequence assay, (2) two-dimensional agarose gel electrophoresis, (3) alkaline gel electrophoresis assay for nascent DNA strands, (4) density transfer method to determine the time of replication, (5) single molecule analysis by molecular combing, and (6) assaying replication on a genomic scale. The intra-S and S/M checkpoints are discussed, with particular attention to the question of what the checkpoint signal is and what is regulated as a response. Checkpoints have been found to promote genome stability by enforcing the ordered execution of cell cycle events and by monitoring the integrity of intracellular structures. Genetic and biochemical analyses have revealed several checkpoint pathways––that is, signals that are recognized at different times in the cell cycle and are transduced in different ways to achieve different effects.