Kathrin Gerstendörfer - AG Jahns

Regulation of the Zeaxanthin Epoxidase

The zeaxanthin epoxidase (ZEP) catalyzes the conversion of zeaxanthin (Zx) to violaxanthin (Vx), a reaction involved in the xanthophyll cycle and abscisic acid (ABA) biosynthesis. In chloroplasts, the ZEP protein is associated with both the thylakoid and envelope membrane, but is further present as soluble protein in the stroma. In thylakoid membranes, Zx has a central photoprotective role in the dissipation of excess light energy. Zx is formed in the xanthophyll cycle from Vx (catalyzed by the Vx de-epoxidase) upon light stress and reconverted to Vx (catalyzed by the ZEP) in low light or darkness. Upon prolonged light stress, ZEP activity is gradually down-regulated concomitant with inactivation of photosystem II (PSII), so that high levels of photoprotective  Zx are retained in chloroplasts for a longer time after pronounced photoinhibition of PSII. Under extreme light stress conditions, ZEP becomes completely inactivated and subsequently degraded along with the degradation of the D1 protein of PSII. In response to drought stress, which activates ABA biosynthesis in chloroplasts and non-green plastids, ZEP is differentially regulated in roots and leaves. In roots, ZEP is upregulated concomitant with ABA biosynthesis, while ZEP is degraded in leaves. The detailed understanding of the regulation of ZEP is crucial for the understanding of the dual role of ZEP in photoprotection and ABA biosynthesis.

 

 

Starting date: 01.11.2014 / PhD student

Thesis committee members: 

Mini Academic CV:

  • 2014:
    • M.Sc. Plant Sciences, Universität Bonn


      Thesis: Genetic Analysis of Lipid metabolism in Nannochloropsis oceanica CCMP1779 (research at the Michigan State University Group of Prof. Christoph Benning)

  • 2012:
    • Bachelor of Applied Biology, Fachhochschule Bonn Rhein-Sieg
  

     

    • Thesis: Functional characterization of genes related to lipid metabolism in the green model alga Chlamydomonas reinhardtii (research at the Universität Bonn Group of Prof. Peter Dörrmann) 
Responsible for the content: E-MailDr. Petra Fackendahl