Related Experiment Video
Updated: Jul 10, 2026

A New Approach for the Comparative Analysis of Multiprotein Complexes Based on 15N Metabolic Labeling and Quantitative Mass Spectrometry
Published on: March 13, 2014
A highly active histidine-tagged Chlamydomonas reinhardtii Photosystem II preparation for structural and biophysical
Matthew Cullen1, Nicola Ray, Sally Husain
1Division of Molecular Biosciences, Faculty of Natural Sciences, Imperial College London, South Kensington, London, UK SW7 2AZ.
Abstract:
We describe a genetically engineered strain of Chlamydomonas reinhardtii where the PsbH subunit of Photosystem II (PSII) has been modified to include a C-terminal polyhistidine tag. The strain was generated by the rescue to photoautotrophic growth of a psbH insertional mutant following chloroplast transformation with the modified gene. This selection strategy confirms that the addition of the tag to PsbH does not prevent the assembly of functional PSII, and results in an engineered strain with tagged PSII but no antibiotic-resistance markers in the chloroplast genome. Consequently, the strain is suitable for subsequent genetic manipulation of chloroplast PSII genes. We also describe a rapid PSII isolation procedure that gives a preparation capable of high rates of oxygen evolution. This preparation is suitable for spectroscopic analysis as shown by EPR analysis of the S2 state of the water oxidation cycle. Furthermore, electron microscopy, coupled to single particle analysis, has revealed the isolated PSII to be structurally homogeneous core dimers that are ideally suited for higher resolution structural studies.
Related Concept Videos
Photosystem II
The pigment molecules are arranged across two photosystem domains — the antenna complex and the reaction center. The main aim of the pigment molecules...
Photosystems
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...
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...
The Photochemical Reaction Center
Channel Rhodopsins
Rhodopsins belong to the family of cell surface proteins called G-protein coupled receptors,...
The Antenna Complex
