Navigation Links
Photosynthesis: The last link in the chain
Date:1/4/2013

For almost 30 years, researchers have sought to identify a particular enzyme that is involved in regulating electron transport during photosynthesis. A team at Ludwig-Maximilians-Universitt (LMU) in Munich has now found the missing link, which turns out to be an old acquaintance.

Photosynthesis sustains life on Earth by providing energy-rich compounds and the molecular oxygen that higher organisms depend on. The process is powered by sunlight, which is captured by "biochemical solar cells" called photosystems that are found in plants, algae and certain types of bacteria. Plants have two photosystems, PSI and PSII. Each consists of a pigment-protein complex that uses solar energy to raise electrons to a higher energy level. These are then passed along a chain of electron acceptors, and the energy released is employed for synthesis of ATP, the "coinage" used for all energy transactions in cells.

Electron transport can proceed along several different routes. So-called linear electron transport requires the participation of both PSI and PSII, and delivers the electrons to a small molecule called NADP, forming NADPH. Cyclic electron flow on the other hand - which can take two alternative paths - involves only PSI, and is used solely for the production of ATP. Electrons that follow the major route are passed via an acceptor called plastoquinone to the cytochrome b6f complex and from there back to PSI, thus completing the cycle.

"The identity of the carrier that donates electrons to plastoquinone, and thus makes the process of cyclic electron flow possible, has long been a subject of controversy," says LMU biologist Professor Dario Leister, who, together with other members of his group, has now succeeded in identifying the crucial missing link in the process.

The crossroads that closes the circuit

Plants can switch between linear and cyclic modes of electron transport in order to maintain the appropriate balance between ATP and NADPH, both of which are required for synthesis of sugars from CO2. This implies that the allocation of electrons between the photosystems can be regulated. An electron transporter called ferredoxin, which receives electrons directly from PSI, acts as the junction that connects the two. "It was therefore proposed, more than 30 years ago, that a so-called ferredoxin-plastoquinone reductase (FQR) must exist, which ensures that electrons can be re-injected into the electron transport chain, and thus allows for cyclic electron transport," Leister explains, "but despite intensive searches, no such enzyme had been found."

In 2008, Leister's team identified a protein they called PGRL1, and showed that it was able to interact with PSI and with other factors known to participate in cyclic electron transport. In their latest study, they have been able to characterize the precise biochemical function of PGRL1. It turns out that the protein is the long-sought FQR that plays a central role in the regulation of cyclic electron flow. "In the long term, this finding may help us to improve photosynthetic performance by replacing or modifying specific components of the electron transport chain," Leister points out.

Pivotal regulators such as PGRL1 could possibly be tuned in a targeted fashion so as to enhance the efficiency of photosynthesis and thus increase yields in crop plants grown under controlled conditions. Furthermore, a complete understanding of the structure and regulation of the photosystems is a prerequisite for the development of methods that would allow one to optimize the process of photosynthesis for various applications such as raising crop yields, designing new types of solar cells or generating molecular hydrogen for use as an environmentally friendly energy source.


'/>"/>

Contact: Kathrin Bilgeri
kathrin.bilgeri@lmu.de
49-892-180-6938
Ludwig-Maximilians-Universitt Mnchen
Source:Eurekalert

Related biology news :

1. Oil and water: An icy interaction when oil chains are short, but steamy when chains are long
2. Chain reaction in the human immune system trapped in crystals
3. Pilot Results Move GHX Closer to Delivery of Healthcare Industrys First Implantable Device Supply Chain Solution
4. Stanford scientists document fragile land-sea ecological chain
5. Copper chains: Study reveals Earths deep-seated hold on copper
6. Study confirms oil from Deepwater Horizon disaster entered food chain in the Gulf of Mexico
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:3/20/2017)... 20, 2017 At this year,s CeBIT Chancellor Dr. ... manufacturer DERMALOG. The Chancellor came to the DERMALOG stand together with the ... year,s CeBIT partner country. At the largest German biometrics company the two ... face and iris recognition as well as DERMALOGĀ“s multi-biometrics system.   ... ...
(Date:3/13/2017)... Future of security: Biometric Face Matching software  Continue ... ... to match face pictures against each other or against large databases. The recognition ... ... software for biometric Face Matching on the market. The speed is at 100 ...
(Date:3/7/2017)... Brandwatch , the leading social intelligence company, today announces that ... uncover insights to support its reporting, help direct future campaigns, and ... youth charity will be using Brandwatch Analytics social listening and analytics ... of the topics and issues that are a priority for its ... "Until recently ...
Breaking Biology News(10 mins):
(Date:3/23/2017)... ... March 23, 2017 , ... Ellen Matloff, ... Connecticut Technology Council (CTC) as a 2017 Women of Innovation® finalist. Matloff will ... Innovation Awards Dinner. , The dinner recognizes women accomplished in science, technology, engineering ...
(Date:3/23/2017)... March 23, 2017 In today,s ... equities in the Biotech industry: Sangamo Therapeutics Inc. (NASDAQ: ... (NYSE MKT: SYN), and Regulus Therapeutics Inc. (NASDAQ: ... 2017, Credit Suisse upgraded its rating on Pharmaceuticals/Biotechnology to "Overweight" from "Market ... free report at: ...
(Date:3/22/2017)... Calif. , March 22, 2017  UBM ... proud to announce their extended partnership and the ... be headlined by the 21 st Annual ... Boston, taking place May 3-4, 2017. ... Medical Technology Association (ADVAMED) President and CEO, ...
(Date:3/22/2017)... 22, 2017 MarketNewsUpdates.com News Commentary  ... The traditional ... being pressured as of late due to the rise of ... has a dramatic impact on patient,s quality of life as ... for identifying new forms of opioid formulations that prevent abuse. ...
Breaking Biology Technology: