Distribution of Cd and other cations between the stroma and thylakoids: a quantitative approach to the search for Cd targets in chloroplasts

Plant growth and photosynthetic activity are usually inhibited due to the overall action of Cd on a whole organism, though few cadmium cations can invade chloroplasts in vivo. We found that in vivo, the major portion of Cd in barley chloroplasts is located in the thylakoids (80%), and the minor port...

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Bibliographic Details
Published in:Photosynthesis research 2019-03, Vol.139 (1-3), p.337-358
Main Authors: Lysenko, Eugene A., Klaus, Alexander A., Kartashov, Alexander V., Kusnetsov, Victor V.
Format: Article
Language:English
Subjects:
Barley
Biochemistry
Biomedical and Life Sciences
Cadmium
Cadmium - metabolism
Carbonic anhydrases
Cations
Chloroplasts
Chloroplasts - metabolism
Electron transport
Life Sciences
Original Article
Photosynthesis
Photosynthesis - genetics
Photosynthesis - physiology
Plant Genetics and Genomics
Plant Physiology
Plant Sciences
Plastocyanin
Proteases
Stroma
Thylakoids
Thylakoids - metabolism
Zinc (Metal)
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Summary:Plant growth and photosynthetic activity are usually inhibited due to the overall action of Cd on a whole organism, though few cadmium cations can invade chloroplasts in vivo. We found that in vivo, the major portion of Cd in barley chloroplasts is located in the thylakoids (80%), and the minor portion is in the stroma (20%). Therefore, the electron-transport chain in the thylakoids would be the likely target for direct Cd action in vivo. In vitro, we found the distribution of Cd to be shifted to the stroma (40–60%). In barley chloroplasts, the major portions of Mg, Fe, Mn, and Cu were found to be located in the thylakoids, and most Ca, Zn, and K in the stroma. This finding was true for both control and Cu- or Fe-treated plants. Treatment with Cd affected the contents of all cations, and the largest portions of Ca and Zn were in the thylakoids. Alterations of the K and Mn contents were caused by Cd, Cu, or Fe treatment; the levels of other cations in chloroplasts were changed specifically by Cd treatment. The quantity of Cd in chloroplasts was small in comparison to that of Mg, Ca, and Fe. In thylakoids, the amount of Cd was similar to that of Cu and comparable to the levels of Zn and Mn. Accordingly, the possible targets for direct Cd action in thylakoids are the Mn cluster, plastocyanin, carbonic anhydrase, or FtsH protease. The quantity of Cd in thylakoids is sufficient to replace a cation nearly completely at one of these sites or partially (20–30%) at many of these sites.
ISSN:0166-8595
1573-5079
DOI:10.1007/s11120-018-0528-6