Influence of pH, Mg2+, and lipid composition on the aggregation state of the diatom FCP in comparison to the LHCII of vascular plants

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• 作者：Susann Schaller (1)
  Konstantin Richter (1)
  Christian Wilhelm (1)
  Reimund Goss (1)
  
• 关键词：Fucoxanthin chlorophyll protein ; Diatom ; Light ; harvesting complex ; MGDG ; SQDG ; Thylakoid membrane
• 刊名：Photosynthesis Research
• 出版年：2014
• 出版时间：March 2014
• 年：2014
• 卷：119
• 期：3
• 页码：305-317
• 全文大小：976 KB
• 作者单位：Susann Schaller (1)
  Konstantin Richter (1)
  Christian Wilhelm (1)
  Reimund Goss (1)
  
  1. Institute of Biology, University of Leipzig, Johannisallee 21-23, 04103, Leipzig, Germany
  
• ISSN：1573-5079

文摘

In the present study, the influence of Mg2+ ions and low pH values on the aggregation state of the diatom FCP and the LHCII of vascular plants was studied. In addition, the concentration of thylakoid membrane lipids associated with the complexes was determined. The results demonstrate that the FCP, which contained a significantly higher concentration of the negatively charged lipids SQDG and PG, was less sensitive to Mg2+ and low pH values than the LHCII which was characterized by lower amounts of SQDG and a higher concentration of MGDG. High MgCl2 concentrations and pH values below pH 6 induced significant changes of the absorption and 77K fluorescence emission spectra of the LHCII, indicating a strong aggregation of the light-harvesting complex. This aggregation was also visible as a pellet after centrifugation on a sucrose cushion. Although the FCP responded with changes of the absorption and fluorescence spectra to low pH and Mg2+ incubation, these spectral changes were less pronounced than those observed for the LHCII. In addition, the FCP complexes did not show a visible pellet after incubation with either low pH values or high Mg2+ concentrations. Only the combined action of Mg2+ and pH 5 led to FCP aggregates of a size that could be pelleted by centrifugation. The decreased sensitivity of FCP aggregation to Mg2+ and low pH is discussed with respect to the differences in the concentration of the lipids surrounding the FCP and LHCII and the different thylakoid membrane organizations of diatoms and vascular plants.