PgmNr Y3028: Duplication of the budding yeast spindle pole body.

Authors:
D. Rüthnick; A. Neuner; E. Schiebel


Institutes
Zentrum für Molekulare Biologie Heidelberg (ZMBH), DKFZ-ZMBH Allianz, Heidelberg, DE.


Keyword: Cytoskeleton

Abstract:

The functional equivalent of the centrosome in budding yeast is the spindle pole body (SPB). It is the principle microtubule-organizing center. For centrosomes and SPBs it is crucial that they, just like DNA, duplicate exactly once per cell cycle. During this process the parental structure serves as a nucleation platform for the assembly of the new complex. A major difference in duplication of SPBs and centrosomes arises from the fact that budding yeast undergoes a closed mitosis without nuclear envelope (NE) breakdown. Therefore the new SPB has to be embedded into the NE to fulfill its microtubule organizing functions. The process of SPB duplication starts in anaphase with the elongation of the half bridge into a full bridge. In a next step, the satellite, a miniature version of the SPB, develops at the distal end of this bridge structure on the cytoplasmic side of the NE. After the Start point of the cell cycle the satellite grows into the duplication plaque, which simultaneously becomes inserted into the NE. In the a final step, after the assembly of the nuclear side of the SPB components, the bridge is severed in its center and the two SPBs become the poles of the mitotic spindle.

Our lab is particularly interested in the two major characteristics of the SPB cycle: restricting SPB duplication to one event per cell cycle and insertion of the duplication plaque into the NE. In order to get new insights into these topics we uncoupled duplication plaque formation from NE insertion. We then ask whether the overly large duplication plaque subsequently can be inserted into the NE. For this, we applied standard fluorescence microscopy, super-resolution microscopy (PALM, dSTORM, SIM) and electron microscopy next to a variety of molecular techniques. Our analysis identified novel properties of SPB components and showed that structures as big as 1 µm can be inserted into the NE post-assembly.



Yeast Database Genetic Index
1. gene symbol: SPC42; systematic name: YKL042W
2. gene symbol: SPC110; systematic name: YDR356W