Luis López-Maury | A protease-mediated mechanism regulates cytochrome c6/ plastocyanin switch
Channel: CyanoWorld
Date: 2023-03-01

Luis López-Maury - University of Seville, Spain

Twitter: https://twitter.com/cyanometals
Research Gate: https://www.researchgate.net/profile/Luis-Lopez-Maury

A protease-mediated mechanism regulates cytochrome c6/ plastocyanin switch in cyanobacteria

After the Great Oxidation Event (GOE) iron availability was greatly reduced, and photosynthetic organisms evolved several alternative proteins. One of these proteins is plastocyanin, a type I blue-copper protein that replaces cytochrome c6 as a soluble electron carrier between cytochrome b6f and PSI. In most cyanobacteria, the expression of these two alternative proteins is regulated by copper availability, but the regulatory system remained unknown. Here we provide evidence that the regulatory system is composed by a BlaI/CopY family transcription factor (called PetR) and a BlaR membrane protease (called PetP). PetR represses petE (plastocyanin) expression and activates petJ (cytochrome c6), while PetP controls PetR levels in vivo. Using whole cell extracts, we prove that PetR degradation requires the presence of both PetP and copper. Transcriptomic analysis has revealed that PetRP system regulates only 4 genes (petE, petJ, slr0601, and slr0602), highlighting its specificity. Furthermore, the presence of petE and petRP in early branching/primitive cyanobacteria indicates that acquiring these genes could have been an early adaptation to reduced iron bioavailability after GOE.

This talk is part of the CyanoWorld online seminar series, hosted by Nicolas Schmelling and Ilka Axmann, and was held on Zoom on September 23rd, 2021.

Follow Us on Twitter: https://twitter.com/CyanoWorld1