title: Thylakoid-Bound FtsH Proteins Facilitate Proper Biosynthesis of Photosystem I.
abstract: Thylakoid membrane-bound FtsH proteases have a well-characterized role in degradation of the photosystem II (PSII) reaction center protein D1 upon repair of photodamaged PSII. Here, we show that the Arabidopsis (Arabidopsis thaliana) var1 and var2 mutants, devoid of the FtsH5 and FtsH2 proteins, respectively, are capable of normal D1 protein turnover under moderate growth light intensity. Instead, they both demonstrate a significant scarcity of PSI complexes. It is further shown that the reduced level of PSI does not result from accelerated photodamage of the PSI centers in var1 or var2 under moderate growth light intensity. On the contrary, radiolabeling experiments revealed impaired synthesis of the PsaA/B reaction center proteins of PSI, which was accompanied by the accumulation of PSI-specific assembly factors. psaA/B transcript accumulation and translation initiation, however, occurred in var1 and var2 mutants as in wild-type Arabidopsis, suggesting problems in later stages of PsaA/B protein expression in the two var mutants. Presumably, the thylakoid membrane-bound FtsH5 and FtsH2 have dual functions in the maintenance of photosynthetic complexes. In addition to their function as a protease in the degradation of the photodamaged D1 protein, they also are required, either directly or indirectly, for early assembly of the PSI complexes.
authors.affiliation: Molecular Plant Biology, Department of Biochemistry, University of Turku, FI-20520 Turku, Finland (S.J., M.S., A.I., S.R., Y.A., E.-M.A.); andPlant Molecular Biology (Botany), Department of Biology I, Ludwig-Maximilians-Universität München, 82152 Planegg-Martinsried, Germany (L.T., D.L.).
authors.forename: Sari
authors.identifier: 0000-0003-4235-9292
authors.initials: S
authors.lastname: Järvi
authors.affiliation: Molecular Plant Biology, Department of Biochemistry, University of Turku, FI-20520 Turku, Finland (S.J., M.S., A.I., S.R., Y.A., E.-M.A.); andPlant Molecular Biology (Botany), Department of Biology I, Ludwig-Maximilians-Universität München, 82152 Planegg-Martinsried, Germany (L.T., D.L.).
authors.forename: Marjaana
authors.identifier: 0000-0002-3821-0607
authors.initials: M
authors.lastname: Suorsa
authors.affiliation: Molecular Plant Biology, Department of Biochemistry, University of Turku, FI-20520 Turku, Finland (S.J., M.S., A.I., S.R., Y.A., E.-M.A.); andPlant Molecular Biology (Botany), Department of Biology I, Ludwig-Maximilians-Universität München, 82152 Planegg-Martinsried, Germany (L.T., D.L.).
authors.forename: Luca
authors.identifier: 0000-0003-2315-7695
authors.initials: L
authors.lastname: Tadini
authors.affiliation: Molecular Plant Biology, Department of Biochemistry, University of Turku, FI-20520 Turku, Finland (S.J., M.S., A.I., S.R., Y.A., E.-M.A.); andPlant Molecular Biology (Botany), Department of Biology I, Ludwig-Maximilians-Universität München, 82152 Planegg-Martinsried, Germany (L.T., D.L.).
authors.forename: Aiste
authors.identifier: 0000-0002-1149-5243
authors.initials: A
authors.lastname: Ivanauskaite
authors.affiliation: Molecular Plant Biology, Department of Biochemistry, University of Turku, FI-20520 Turku, Finland (S.J., M.S., A.I., S.R., Y.A., E.-M.A.); andPlant Molecular Biology (Botany), Department of Biology I, Ludwig-Maximilians-Universität München, 82152 Planegg-Martinsried, Germany (L.T., D.L.).
authors.forename: Sanna
authors.identifier: 0000-0001-8106-2657
authors.initials: S
authors.lastname: Rantala
authors.affiliation: Molecular Plant Biology, Department of Biochemistry, University of Turku, FI-20520 Turku, Finland (S.J., M.S., A.I., S.R., Y.A., E.-M.A.); andPlant Molecular Biology (Botany), Department of Biology I, Ludwig-Maximilians-Universität München, 82152 Planegg-Martinsried, Germany (L.T., D.L.).
authors.forename: Yagut
authors.identifier: 0000-0002-9262-1757
authors.initials: Y
authors.lastname: Allahverdiyeva
authors.affiliation: Molecular Plant Biology, Department of Biochemistry, University of Turku, FI-20520 Turku, Finland (S.J., M.S., A.I., S.R., Y.A., E.-M.A.); andPlant Molecular Biology (Botany), Department of Biology I, Ludwig-Maximilians-Universität München, 82152 Planegg-Martinsried, Germany (L.T., D.L.).
authors.forename: Dario
authors.identifier: 0000-0003-1897-8421
authors.initials: D
authors.lastname: Leister
authors.affiliation: Molecular Plant Biology, Department of Biochemistry, University of Turku, FI-20520 Turku, Finland (S.J., M.S., A.I., S.R., Y.A., E.-M.A.); andPlant Molecular Biology (Botany), Department of Biology I, Ludwig-Maximilians-Universität München, 82152 Planegg-Martinsried, Germany (L.T., D.L.) evaaro@utu.fi.
authors.forename: Eva-Mari
authors.identifier: 0000-0002-2922-1435
authors.initials: EM
authors.lastname: Aro
mesh_terms: D049069:ATP-Dependent Proteases / Q000235:genetics / Q000378:metabolism*; D017360:Arabidopsis / Q000378:metabolism* / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D004579:Electron Transport / Q000528:radiation effects; D008027:Light; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D045726:Metalloproteases / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D010788:Photosynthesis / Q000528:radiation effects; D045331:Photosystem I Protein Complex / Q000096:biosynthesis* / Q000378:metabolism; D045332:Photosystem II Protein Complex / Q000378:metabolism; D011485:Protein Binding; D021122:Protein Subunits / Q000378:metabolism; D059748:Proteolysis / Q000528:radiation effects; D020524:Thylakoids / Q000378:metabolism*
chemical_list: D049069:ATP-Dependent Proteases; D029681:Arabidopsis Proteins; D008565:Membrane Proteins; D045726:Metalloproteases; D045331:Photosystem I Protein Complex; D045332:Photosystem II Protein Complex; D021122:Protein Subunits; C547215:FtsH5 protein, Arabidopsis; C402651:AT2G30950 protein, Arabidopsis