Hidden behind the mean: single cell analysis of the membrane recruitment dynamics of yeast mating MAPK pathway scaffold protein

VICTORIA REPETTO; ALAN BUSH; MATTHEW WINTERS; PETER PRYCIAK; ALEJANDRO COLMAN LERNER

Los Cocos

Congreso; The Second South American Symposium on Signal Transduction and Translational Medicine; 2012

SISTAM

A prototypical scaffold protein is Ste5, which coordinates the yeast mating mitogen-activated protein kinase (MAPK) response by binding to all three components of the MAPK cascade. Far away from being a passive scaffolding-platform, it has become noticeable that Ste5 can directly receive input information, either from the activated pheromone receptor1 or the inhibitory phosphorylations by the cell-cycle dependent kinase2, and process the signal to be transmitted to mating output. In order to gain a deeper understanding of the active rol of Ste5 in the process of fate-decision upon pheromone induction, we followed in real-time recruitment of Ste5 to the membrane in single cells and obtained quantitative measurements using Cell-ID coupled to the statistical programming framework R for data analysis3. The quantitative analysis of single cell phenotypes revealed a graded heterogeneity in the response that showed correlation with the cell cycle position. The regulation of the dynamic was dependent of Ste5 cell-cycle dependent kinase regulatory sites and required the kinase activity of the matting pathway MAPK Fus3. These results highlight a required interplay between the cell-cycle components and the activated pheromone MAPK to determine the cell-fate decision. 1Zalatan et al. Science 337:1218 (2012) 2Strickfaden et al. Cell 128:519 (2007) 3Chernomoretz et al. Curr. Protoc. Mol. Biol. 84:14.18.1 (2008)