Related Experiment Video
Updated: Jun 29, 2026
10:09
Photobleaching Enables Super-resolution Imaging of the FtsZ Ring in the Cyanobacterium Prochlorococcus
Published on: November 6, 2018
The peripheral light-harvesting complexes from purple sulfur bacteria have different 'ring' sizes
Sami Kereïche1, Laurent Bourinet, Wilko Keegstra
1Department of Biophysical Chemistry, Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands.
FEBS Letters
|October 9, 2008
Summary
Researchers discovered new ring sizes for light-harvesting (LH) proteins in purple bacteria. These findings expand our understanding of how these proteins assemble into membrane rings, crucial for photosynthesis.
Area of Science:
- Biochemistry
- Microbiology
- Photosynthesis Research
Background:
- Integral membrane light-harvesting (LH) proteins in purple photosynthetic bacteria form circular oligomers.
- These proteins consist of alpha and beta polypeptides and assemble into arrays of 8, 9, and 16 units.
Purpose of the Study:
- To investigate the structural diversity of light-harvesting protein oligomers.
- To identify novel ring sizes of peripheral LH proteins in Allochromatium vinosum.
Main Methods:
- Purification of peripheral LH proteins from Allochromatium vinosum.
- Analysis of protein oligomer ring sizes.
Main Results:
- Identification of peripheral LH proteins with intermediate ring sizes.
- Postulation of a 13 alpha/beta-mer ring size.
- Demonstration of LH protein ring formation with diameters ranging from 68 to 115 Angstroms.
Conclusions:
- The existence of new ring sizes indicates a broader capacity for LH protein assembly.
- These findings necessitate further investigation to refine structure-function models of LH proteins.
Related Concept Videos
01:28Anoxygenic Phototrophic Bacteria
Anoxygenic phototrophic bacteria are a diverse group of microorganisms that perform photosynthesis without producing oxygen. They primarily include purple sulfur bacteria, purple nonsulfur bacteria, green sulfur bacteria, and green nonsulfur bacteria. These bacteria are classified into the Gammaproteobacteria, Alphaproteobacteria, Betaproteobacteria, Chlorobi, and Chloroflexi lineages, each with distinct physiological and ecological adaptations.Purple sulfur bacteria belong to the...
01:30Anoxygenic Photosynthesis
Anoxygenic photosynthesis is a phototrophic process that captures light energy to drive carbon fixation without producing molecular oxygen. Unlike oxygenic photosynthesis, which utilizes water as an electron donor and releases oxygen, anoxygenic phototrophs use alternative electron donors such as hydrogen sulfide (H₂S), elemental sulfur (S⁰), or thiosulfate (S₂O₃²⁻). This process is carried out by diverse groups of bacteria, including purple bacteria, green sulfur bacteria, heliobacteria, and...
01:15The Antenna Complex
Plants and other photosynthetic organisms comprise pigments capable of absorption of direct sunlight. These pigments are present in the reaction center - the main site of photochemical reactions as well as in the antenna complex. Under average light conditions, the rate at which reaction center pigments absorb light is far below the electron transport chain's capacity. As a result, the reaction center alone cannot provide enough energy to drive photosynthesis. The photosynthetic efficiency can...
01:29The Photochemical Reaction Center
Reaction centers are pigment-protein complexes that initiate energy conversion from photons to chemical entities. Therefore, photochemical reaction center is a more appropriate term that describes these complexes. The Nobel laureates Robert Emerson and William Arnold provided the first experimental evidence of photochemical reaction centers by demonstrating the participation of nearly 2,500 chlorophyll molecules for the release of just one molecule of oxygen. Despite thousands of photosynthetic...
01:32Photosystems
Photosystems are multiprotein complexes that form the functional units of photosynthesis in plants, algae, and cyanobacteria. They are found embedded in the membrane of tiny sac-like structures called thylakoids placed inside the chloroplast.
Functioning of Photosystems
Photosystems contain many pigment molecules, such as chlorophylls and carotenoids, arranged in a particular organization across two domains — the antenna complex and the reaction center. The main aim of the pigment molecules...
Functioning of Photosystems
Photosystems contain many pigment molecules, such as chlorophylls and carotenoids, arranged in a particular organization across two domains — the antenna complex and the reaction center. The main aim of the pigment molecules...
01:27Photosystem I
Although structurally similar to photosystem II (PSII), photosystem I (PSI) is has a different electron supplier and electron acceptor.
Both these photosystems work in concert. An excited electron from PSII is relayed to PSI via an electron transport chain in the thylakoid membrane of the chloroplast, which is comprised of the carrier molecule plastoquinone, the dual-protein cytochrome complex, and plastocyanin. As electrons move between PSII and PSI, they lose energy and must be re-energized...
Both these photosystems work in concert. An excited electron from PSII is relayed to PSI via an electron transport chain in the thylakoid membrane of the chloroplast, which is comprised of the carrier molecule plastoquinone, the dual-protein cytochrome complex, and plastocyanin. As electrons move between PSII and PSI, they lose energy and must be re-energized...