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The transit peptide of CP29 thylakoid protein in Chlamydomonas reinhardtii is not removed but undergoes acetylation and phosphorylation
Linköping University, Department of Clinical and Experimental Medicine, Cell Biology. Linköping University, Faculty of Health Sciences.
Umeå Plant Science Center, Department of Plant Physiology, University of Umeå, Umeå, Sweden.
Linköping University, Department of Clinical and Experimental Medicine, Cell Biology. Linköping University, Faculty of Health Sciences.
2004 (English)In: FEBS letters, ISSN 0014-5793, Vol. 564, no 1-2, 104-108 p.Article in journal (Refereed) Published
Abstract [en]

The surface-exposed peptides were cleaved by trypsin from the photosynthetic thylakoid membranes isolated from the green alga Chlamydomonas reinhardtii. Two phosphorylated peptides, enriched from the peptide mixture and sequenced by nanospray quadrupole time-of-flight mass spectrometry, revealed overlapping sequences corresponding to the N-terminus of a nuclear-encoded chlorophyll a/b-binding protein CP29. In contrast to all known nuclear-encoded thylakoid proteins, the transit peptide in the mature algal CP29 was not removed but processed by methionine excision, N-terminal acetylation and phosphorylation on threonine 6. The importance of this phosphorylation site is proposed as the reason of the unique transit peptide retention.

Place, publisher, year, edition, pages
2004. Vol. 564, no 1-2, 104-108 p.
Keyword [en]
Transit peptide, Thylakoid membrane, CP29, Protein phosphorylation, Mass spectrometry, Chlamydomonas reinhardtii
National Category
Medical and Health Sciences
URN: urn:nbn:se:liu:diva-12928DOI: 10.1016/S0014-5793(04)00323-0OAI: diva2:17414
Available from: 2008-02-06 Created: 2008-02-06 Last updated: 2009-06-05
In thesis
1. Functional proteomics of protein phosphorylation in algal photosynthetic membranes
Open this publication in new window or tab >>Functional proteomics of protein phosphorylation in algal photosynthetic membranes
2008 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Plants, green algae and cyanobacteria perform photosynthetic conversion of sunlight into chemical energy in the permanently changing natural environment. For successful survival and growth photosynthetic organisms have developed complex sensing and signaling acclimation mechanisms. The environmentally dependent protein phosphorylation in photosynthetic membranes is implied in the adaptive responses; however, the molecular mechanisms of this regulation are still largely unknown. We used a mass spectrometry-based approach to achieve a comprehensive mapping of the in vivo protein phosphorylation sites within photosynthetic membranes from the green alga Chlamydomonas reinhardtii subjected to distinct environmental conditions known to affect the photosynthetic machinery.

The state transitions process regulating the energy distribution between two photosystems, involves the temporal functional coupling of phosphorylated light-harvesting complexes II (LHCII) to photosystem I (PSI). During state transitions several of the thylakoid proteins undergo redox-controlled phosphorylation-dephosphorylation cycles. This work provided evidences suggesting that redox-dependent phosphorylation-induced structural changes of the minor LHCII antenna protein CP29 determine the affinity of LHCII for either of the two photosystems. In state 1 the doubly phosphorylated CP29 acts as a linker between the photosystem II (PSII) core and the trimeric LHCII whereas in state 2 this quadruply phosphorylated CP29 would migrate to PSI on the PsaH side and provide the docking of LHCII trimers to the PSI complex. Moreover, this study revealed that exposure of Chlamydomonas cells to high light stress caused hyperphosphorylation of CP29 at seven distinct residues and suggested that high light-induced hyperphosphorylation of CP29 may uncouple this protein together with LHCII from both photosystems to minimize the damaging effects of excess light.

Reversible phosphorylation of the PSII reaction center proteins was shown to be essential for the maintenance of active PSII under high light stress. Particularly dephosphorylation of the light-damaged D1 protein, a central functional subunit of the PSII reaction center, is required for its degradation and replacement. We found in the alga the reversible D1 protein phosphorylation, which until our work, has been considered as plant-specific.

We also discovered specific induction of thylakoid protein phosphorylation during adaptation of alga to limiting environmental CO2. One of the phosphorylated proteins has five phosphorylation sites at both serine and treonine residues. The discovered specific low-CO2- and redox-dependent protein phosphorylation may be an early adaptive and signalling response of the green alga to limitation in inorganic carbon.

This work provides the first comprehensive insight into the network of environmentally regulated protein phosphorylation in algal photosynthetic membranes.

Place, publisher, year, edition, pages
Linköping University Electronic Press, 2008. 40 p.
Linköping University Medical Dissertations, ISSN 0345-0082 ; 1038
Protein phosphorylation, mass spectrometry, photosynthesis, proteomics
National Category
Biochemistry and Molecular Biology
urn:nbn:se:liu:diva-10708 (URN)978-91-85523-02-3 (ISBN)
Public defence
2008-02-29, Linden, ingång 65, Hälsouniversitetet, Linköping, 13:00 (English)
Available from: 2008-02-06 Created: 2008-02-06 Last updated: 2015-11-19

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Turkina, Maria VVener, Alexander V.
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