Subzelluläre Verteilung von Proteintranslation und Translokation in der Hefe Saccharomyces cerevisiae
Zusammenfassung der Projektergebnisse
Proteins perform their functions at specific cellular locations. These locations can change during the cell cycle or upon external or internal stimuli. During the funding period we followed three approaches to learn more about different protein targeting mechanisms. 1. We established the Ub-Trap method which allowed us to monitor the bud specific translation of Ash1, a repressor of transcription in the nucleus of daughter cells. Furthermore, we could show that the transmembrane protein Wcs2 is preferentially synthesized at the cortical ER of the bud, whereas the homologous Wsc3 is equally synthesized at the ER of mother and future daughter cell. We could show with the help of the Ub-Trap method, that translation of the polarisome component Pea2, although residing at the tip of the bud, does not occur preferentially at this position. 2. A collaborative effort established the changes in composition and location of the yeast proteome during the cell cycle. We specifically contributed to the understanding of the dynamic cellular distribution of the uncharacterized protein YMR295C. Our protein interaction screen revealed with Fks1/2 and Rho1 three interaction partners that could explain the distribution of YMR295C and point to a function of YMR295C in cell wall synthesis or surveillance. 3. The polarisome scaffold Spa2 anchors the proteins Msb3, Msb4, and Ste7 to the tip of buds and mating projections. We could show that the interactions occur between a groove of the SHD1 domain of Spa2 and a short motif, that is shared between the three binding partners. AlphaFold predicts that this motif folds into a helix that perfectly fits into the groove. Our AlphaFold analysis further showed, that the same motif can be found in the sequences of known and suspected binding partners of homologues of Spa2 of other yeasts, fungi and metazoans, including humans.
