Some speculations concerning the evolution of photosynthetic function

Area of Science:

• Biochemistry
• Evolutionary Biology
• Photosynthesis Research

Background:

• Photosynthetic reaction centers (RCs) perform crucial light-driven charge separation.
• Understanding the evolution of RCs is key to comprehending early life.
• Contemporary RCs possess remarkable efficiency and complex structures.

Purpose of the Study:

• Investigate the reason for the extreme speed of the initial charge separation in RCs.
• Propose a model for a primitive RC structure and its evolutionary path.
• Explore the functional significance of RC complexity and its origins.

Main Methods:

• Review of light-driven reactions in photosynthetic membranes.
• Hypothetical modeling of primitive reaction centers.
• Speculation on evolutionary pathways based on current RC structure and function.

Main Results:

• Primary charge separation is optimized to outcompete detrapping into antenna complexes.
• A concept of 'kinetic perfection' is proposed for ultra-fast biological processes.
• The iron-quinone part of the RC is suggested as a potential primitive photosynthetic unit.

Conclusions:

• The complexity of modern RCs suggests they did not serve as early functional units.
• Primitive antenna complexes likely evolved later, associating with simpler RCs.
• The study offers testable hypotheses regarding RC evolution and function.