High-speed shooting reveals protein changes during photosynthesis

Photosynthesis is the main source of energy for nearly all life on earth. A new study, published in Nature, provide new insights into how evolution has optimized the light-guided movements of electrons in photosynthesis to achieve near-perfect overall efficiency.

Almost all life on earth has the energy transduction reactions of photosynthesis as the primary source of energy. These light-driven reactions occur in plants, algae, and photosynthetic bacteria.

The X-ray structure of a protein provides scientists with a lot of information about how they perform their biological task in a living cell.

X-ray films show structural changes within a protein

In this work, the scientists used a method called time-resolved X-ray crystallography to film the structural changes within the protein responsible for the chemical reactions of light-guided photosynthesis. To achieve this, scientists from the University of Gothenburg used a world-leading X-ray source in California (an X-ray-free electron laser) to examine whether structural rearrangements within photosynthetic proteins occur. in the time it takes for the light to cross the hair. of your head. Surprisingly, these measurements showed that the structure of the protein changes on this time scale.

Subtle movements were observed in the protein

Scientists at the University of Gothenburg observed that these movements were very subtle, both with the electron donor (a chemical group that absorbs light and releases an electron) and with the electron acceptor (a chemical group found at 2 nm away and receiving this electron) moving less than 0.03 nm (1 nm = 10^-9 m or one millionth of a millimeter) into 300 ps (1 ps = 10^-12 sec is called the picosecond and is one millionth of a millionth of a second).

The protein as a whole also changed its structure slightly to prevent the electron from returning to where it started, which would otherwise render the reaction useless. These findings are critical to how evolution has optimized energy transducer proteins over billions of years to enable them to perform redox reactions without energy being lost in the process.

“Time-resolved crystallographic studies of a photosynthetic protein from bacteria reveal how light-induced electron movements are stabilized by structural changes in the protein occurring on a picosecond time scale,” says Richard Neutze, a professor at the University of Gothenburg.