PSC Frontier Seminar series
Title: GUN control of retrograde signaling
Speaker: Prof. Ralph Bock
Time: 14:00 pm
Day/Date: Apr. 15th, 2019 (Monday)
Host: Prof. Chanhong Kim
Venue: PSC auditorium
Communication between organelles and the nucleus is essential for fitness and survival. In plants, signals from plastids (chloroplasts) couple the expression of nuclear genes with plastid function, a phenomenon known as retrograde signalling. Genetic screens in Arabidopsis identified an mutant called gun1 that is defective in retrograde signaling. The GUN1 gene encodes a putative pentatricopeptide repeat (PPR) protein that localizes to plastids. It has been proposed to act as the central integrator of a number of different retrograde signals and relay information to the nucleus by targeting multiple nuclear transcription factors. However, although the gun1 mutant was isolated more than 25 years ago, the molecular functions of GUN1 in retrograde communication and signaling have remained enigmatic. Using an array of genetic, cell biological and biochemical approaches, we have determined the function of GUN1. Our data challenge the classical model of GUN signaling and suggest an entirely new model, in which chloroplast protein import capacity, protein folding stress and cytosolic chaperones control retrograde communication from stressed chloroplasts.
The seminar will be delivered in English.