Related Experiment Video
Updated: Jul 3, 2026

Isolation and Characterization of Intact Phycobilisome in Cyanobacteria
Published on: November 10, 2021
Plastocyanin-ferredoxin oxidoreduction and endosymbiotic gene transfer
1Department of Biology, Central Connecticut State University, 1615 Stanley St., New Britain, CT, 06050, USA. carterd@ccsu.edu
Abstract:
Sequence similarities of proteins associated with plastocyanin-ferredoxin oxidoreduction (PcFdOR) activity of Photosystem I (PSI) were grouped and compared. PsaA, psaB, psaC, and petG represent genes that have been retained in the chloroplasts of both green- and red-lineage species. PsaD, psaE, psaF, and petF represent genes that have been retained in the chloroplast of red-lineage species, but have been transferred to the nuclear genome of green-lineage species. Translated sequences from red- and green-lineage proteins were compared to that of contemporary cyanobacteria, Synechocystis PCC 6803, and Gloeobacter violaceus PCC 7421. Within the green lineage, a lower level of sequence conservation coincided with gene transfer to the nuclear genome. Surprisingly, a similar pattern of sequence conservation existed for the same set of genes found in the red lineage even though all those genes were retained in their chloroplast genomes. This discrepancy between green and red lineage is discussed in terms of endosymbiotic gene transfer.
Related Concept Videos
Export of Mitochondrial and Chloroplast Genes
Anoxygenic Photosynthesis
The Anatomy of Chloroplasts
Structure of Chloroplasts
A...
Eukaryotic Evolution
Contrary to the endosymbiont theory, the eukaryote-first hypothesis proposes that the simpler prokaryotic and...
Photosystem I
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...
Oxygenic Photosynthesis

