Biological complexity: photosynthesis, new control found (Introduction)

by David Turell , Tuesday, March 09, 2021, 22:30 (1355 days ago) @ David Turell

A new enzyme location is discerned:

https://www.sciencedaily.com/releases/2021/03/210309114304.htm

"Scientists have pinpointed the location of an essential enzyme in plant cells involved in photosynthesis, according to a study published today in eLife.

"The findings overturn conventional thinking about where the enzyme resides in plant cells and suggest a probable role in regulating energy processes as plants adapt from dark to light conditions.

"During photosynthesis, plants convert carbon into energy stores through 'electron transport', involving an enzyme called ferredoxin:NADP(H) oxidoreductase, or FNR.

Plants can switch rapidly between two types of electron transport -- linear electron flow (LEF) and cyclic electron flow (CEF) in response to environmental conditions. The transfer of FNR between membrane structures in the chloroplast, where photosynthesis takes place, has been linked to this switch.

"'Current dogma states that FNR carries out its function in the soluble compartment of the chloroplast, but evidence suggests that the activity of FNR increases when it is attached to an internal membrane," explains first author Manuela Kramer, a PhD student at the School of Biological and Chemical Sciences, Queen Mary University of London, UK. "We needed to find out precisely where FNR is located in the chloroplast, how it interacts with other proteins, and how this affects its activity in order to understand its role in switching between electron transport processes."

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"To understand more about FNR's location, the team generated plants where the enzyme is specifically bound to different proteins called 'tether proteins'...They found that rescue with maize FNR types that strongly bound to the Tic62 tether protein resulted in much higher density of gold FNR labelling in specific, lamellar membrane regions of the thylakoids. This suggests that the distribution of FNR throughout the chloroplast in plant cells is dependent on binding to the tether proteins.

***

"After light acclimatisation, both the wild-type and mutant plants had similar, decreased CEF activity, suggesting that the impact of FNR is related to light-dependent changes in the interactions between the enzyme and tether proteins.

"'Our results show a link between the interaction of FNR with different proteins and the activity of an alternative photosynthetic electron transport pathway," concludes senior author Guy Hanke"

Comment: photosynthesis is a highly complex process which is vital for oxygen production. Design required.