Optogenetics reveals Cdc42 local activation by scaffold-mediated positive feedback and Ras GTPase

• DOI: 10.1371/journal.pbio.3000600
• Publication Date: 2020-01-24T19:11:09Z
• Authors: Iker Lamas; Laura Merlini; Aleksandar Vještica; Vincent Vincenzetti; Sophie G. Martin
• Keywords: CDC42; Cell polarity; Small GTPase

Local activity of the small GTPase Cdc42 is critical for cell polarization. Whereas scaffold-mediated positive feedback was proposed to break symmetry budding yeast cells and produce a single zone activity, existence similar regulation has not been probed in other organisms. Here, we address this problem using rod-shaped fission Schizosaccharomyces pombe, which exhibit zones active Cdc42-GTP at both poles. We implemented CRY2-CIB1 optogenetic system acute light-dependent protein recruitment plasma membrane, allowed directly demonstrate feedback. Indeed, constitutively leads co-recruitment guanine nucleotide exchange factor (GEF) Scd1 endogenous Cdc42, manner dependent on scaffold Scd2. show that Scd2 function dispensable when operates through an engineered interaction between GEF effector, p21-activated kinase 1 (Pak1). Remarkably, rewired confers viability allows form 2 even otherwise essential activators are lacking. These further revealed Ras1 plays role localizing promoting its potentiates conclude feedback, gated by Ras robust polarization rod-shape formation.