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Shared thematic elements in photochemical reaction centers
1Department of Biochemistry, University of Nebraska, Lincoln 68583-0718.
Summary
Photosystem II and purple nonsulfur bacteria share "quinone-type" (type II) electron acceptors, while Photosystem I and green sulfur bacteria share "iron-sulfur type" (type I) acceptors. This suggests a common evolutionary origin for all photochemical reaction centers.
Area of Science:
- Biochemistry
- Molecular Biology
- Evolutionary Biology
Background:
- Photosystem II and purple nonsulfur bacterial reaction centers are classified as "quinone type" (type II) photosystems.
- Photosystem I and green sulfur bacterial reaction centers are classified as "iron-sulfur type" (type I) photosystems.
Purpose of the Study:
- To review and compare the biochemistry of reaction centers in prokaryotic bacteria, cyanobacteria, and green plants.
- To explore the structural, functional, and evolutionary relationships between different types of photosystems.
Main Methods:
- Comparative analysis of reaction center structures and functions.
- Review of existing biochemical and evolutionary data.
Main Results:
- Type II photosystems utilize a mobile quinone molecule as the terminal electron acceptor.
- Type I photosystems use bound iron-sulfur clusters as the terminal electron acceptor.
- Both type I and type II reaction centers share a common early charge separation motif.
Conclusions:
- The shared motif suggests a common evolutionary origin for all photochemical reaction centers.
- Understanding these relationships provides insight into the evolution of photosynthesis.