engleski

New alleys in regulation of photosynthetic energy conversion

We have recently characterized thylakoid rhodanase-like protein (TROL) which is involved in tethering of the flavo-enzyme ferredoxin:NADP+ oxidoreductase (FNR). FNR is responsible for the final energy transfer in photosynthesis, from ferredoxin to NADP+. Generated NADPH is utilized in CO2 fixation, as well as in various other redox reactions in chloroplasts and entire plant cell. TROL is located at non-appressed regions of thylakoid membranes, in the vicinity of photosystem I (PSI). TROL is a polytopic multi-domain protein which contains rhodanese homology domain (RHO) located in thylakoid lumen, FNR-binding region (ITEP) exposed to chloroplast stroma, and a flexible proline-rich swivel (PEPE) connecting RHO with the ITEP. By using gene inactivation approach in the model plant Arabidopsis, we have addressed functions of TROL in photosynthestic energy conversion. Trol plants in high-light conditions have decreased electron transfer rate (ETR) and increased non-photochemical quenching (NPQ), which indicates that without TROL FNR is no longer able to efficiently catalyze NADPH synthesis. To further address the function of various TROL domains, we have generated complementation lines of Trol which either have amino acid substitutions in the RHO domain, or completely lack RHO, PEPE or ITEP. Functions of TROL and its domains will be discussed in the perspective of photosynthetic electron flow regulation in vascular plants.

New alleys in regulation of photosynthetic energy conversion

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