The spindle pole body of Saccharomyces cerevisiae: Architecture and assembly of the core components

Abstract

The budding yeast spindle pole body (SPB) is a multilayered cylindrical organelle that is embedded in the nuclear envelope throughout the cell cycle. This chapter focuses on the assembly, organization, and regulation of the core of the SPB. The SPB functions as the microtubule organizing center (MTOC) in the budding yeast Saccharomyces cerevisiae, in a manner analogous to the centrosome of animal cells. It is the only MTOC in the yeast cell, serving to initiate nuclear microtubules that form the mitotic spindle as well as cytoplasmic microtubules that position the nucleus and align the spindle during cell division. Monoclonal antibodies prepared against enriched SPB fraction led to the identification of three abundant and essential SPB constituents: Spc110p, Spc42p, and Spc98p. The critical part of the SPB is the γ-tubulin complex consisting of Spc97p, Spc98p, and Tub4p and found in both the inner and outer plaques. A composite picture of the structure of the SPB core can be drawn from immunolocalization, biochemical, and genetic data. Once the yeast genome is sequenced, the highly enriched preparations of SPBs are characterized by mass spectrometry to identify 23 spindle pole components.