Low pH induced structural reorganization in thylakoid membranes
Anjana Jajoo1, Milán Szabó, Ottó Zsiros
1School of Life Science, Devi Ahilya University, Indore, India. anjanajajoo@hotmail.com
Biochimica Et Biophysica Acta
|January 18, 2012
Summary
Acidic pH reversibly alters the macro-organization of chloroplast thylakoid membranes, affecting excitation energy distribution between photosystem I and photosystem II. This explains observed changes in fluorescence spectroscopy.
Area of Science:
- Plant Physiology
- Photosynthesis Research
- Biophysics
Background:
- Fluorescence spectroscopy reveals pH-dependent changes in photosystem II and I fluorescence in thylakoid membranes.
- Previous studies suggest pH influences energy distribution between photosystems.
Purpose of the Study:
- To investigate the origin of pH-induced fluorescence changes in thylakoid membranes.
- To elucidate the effect of pH on the macro-organization of membrane complexes.
Main Methods:
- Circular dichroism (CD) spectroscopy on isolated pea thylakoid membranes.
- Treatment with varying pH levels (7.5 to 4.5).
Main Results:
- Acidification reversibly decreased psi-type CD signals, indicating altered macro-organization.
- Excitonic CD remained unchanged, suggesting pigment-pigment interactions were unaffected.
- Changes in macro-organization, not molecular organization, explain fluorescence alterations.
Conclusions:
- Lowering pH significantly impacts the macro-organization of thylakoid membrane complexes.
- This pH-induced macro-organizational change explains the redistribution of excitation energy between photosystem I and II.
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