2. Yeast Cell Architecture and Functions
- Prof. Dr. Horst Feldmann1,2
Published Online: 26 SEP 2012
Copyright © 2012 Wiley-VCH Verlag GmbH & Co. KGaA
Yeast: Molecular and Cell Biology, Second Edition
How to Cite
Feldmann, H. (ed) (2012) Yeast Cell Architecture and Functions, in Yeast: Molecular and Cell Biology, Second Edition, Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, Germany. doi: 10.1002/9783527659180.ch2
Adolf Butenandt Institute, Molecular Biology, Ludwig-Maximilians-Universität M¨nchen, Schillerstr. 44, 80336 M¨nchen, Germany
Ludwig-Thoma-Strasse 22B, 85232 Bergkirchen, Germany
- Published Online: 26 SEP 2012
- Published Print: 22 AUG 2012
Print ISBN: 9783527332526
Online ISBN: 9783527659180
- yeastcell architecture;
- cell envelope;
• This chapter presents an overview of how a cell of S. cerevisiae is built from elementary structures, each of which has been designed to fulfill particular functions in order to guarantee successful propagation of all individuals in a given population, and at the same time respond to the conditions imposed by its (natural) environment. Except for a rigid cell wall, we will encounter all of the organellar structures of a yeast cell in other single-cell as well as in multicellular eukaryotic organisms. Based on this fact and given the uncomplicated handling (both in terms of genetic manipulation and easy preparation of subcellular entities), yeast became the preferred model system in many basic research areas of molecular biology.
• Part of this chapter is devoted to the description of yeast cell morphology and of how subcellular structures can be recognized. Later, in Chapter 4, methods for the isolation of organelles and cellular components will be presented. The yeast cell envelope and, in particular, the rigid cell wall are of utmost importance for a safe life. The cell wall protects against mechanical injury and unwanted ingress of material. On the other hand, the cell wall is not an inflexible cage, but has to be adapted to the changing shape of the cell during growth and propagation in a controlled fashion. The plasma membrane serves many structural and functional obligations – it harbors protein anchors for the cell cytoskeleton, enzymes of cell wall synthesis, receptors for communication with the environment, including osmotic control, and selective transporters for compounds that enter or that leave the cell. We describe in some detail the components (i.e., microtubules and microfilaments) that build up a dynamic cytoskeletal scaffold. The cytoskeleton is mainly designed for two functions in yeast physiology: (i) transport of cargo (from simple molecules through complex structures to whole organelles) across the cell cytoplasm, and (ii) participation in mitosis and meiosis, determining cell polarity during budding or mating as well as septation before cell separation. Motor proteins such as myosins, kinesins, or dynein provide the energy necessary for motility.
• The cell nucleus is the central organelle that handles the duplication of the chromosomes during cell division and the expression of the majority of genetic information. Thereby, the nuclear pores act as instruments controlling the exchange of macromolecules between the nucleus and the cytosol, or sequestration of particular types of factors within the nucleus. These features are paralleled in yeast and mammals, as intense work in both systems has demonstrated. Here, we rather concentrate on morphological aspects and will discuss some functional aspects later in Chapter 8.
• Cellular organelles taking care of protein processing, their cellular distribution, and programmed degradation are the ER, connected to the nuclear membrane, the Golgi apparatus, and the yeast vacuole (which is similar to lysosomes), including the various vesicular bodies that mediate interorganellar transport. Most of the proteins are fabricated by cytoplasmic ribosomes and imported into the ER, which then controls their correct folding. Handed over to the Golgi, the proteins are subjected to various modifications, thus endowing each of them with attributes that facilitate their targeting to the final destination within the cell or label them for exocytosis. Proteins imported into the cell or retrieved from its surface are channeled into this system as well. The intracellular trafficking was one of the earliest issues studied in yeast and opened up ways to look into similar aspects in higher organisms.
• Finally, this chapter briefly outlines the structural and functional characteristics of the mitochondria and the peroxisomes, both of which are organelles also indispensable in higher eukaryotes.