title: Biogenesis of water splitting by photosystem II during de-etiolation of barley (Hordeum vulgare L.).
abstract: Etioplasts lack thylakoid membranes and photosystem complexes. Light triggers differentiation of etioplasts into mature chloroplasts, and photosystem complexes assemble in parallel with thylakoid membrane development. Plastids isolated at various time points of de-etiolation are ideal to study the kinetic biogenesis of photosystem complexes during chloroplast development. Here, we investigated the chronology of photosystem II (PSII) biogenesis by monitoring assembly status of chlorophyll-binding protein complexes and development of water splitting via O2 production in plastids (etiochloroplasts) isolated during de-etiolation of barley (Hordeum vulgare L.). Assembly of PSII monomers, dimers and complexes binding outer light-harvesting antenna [PSII-light-harvesting complex II (LHCII) supercomplexes] was identified after 1, 2 and 4 h of de-etiolation, respectively. Water splitting was detected in parallel with assembly of PSII monomers, and its development correlated with an increase of bound Mn in the samples. After 4 h of de-etiolation, etiochloroplasts revealed the same water-splitting efficiency as mature chloroplasts. We conclude that the capability of PSII to split water during de-etiolation precedes assembly of the PSII-LHCII supercomplexes. Taken together, data show a rapid establishment of water-splitting activity during etioplast-to-chloroplast transition and emphasize that assembly of the functional water-splitting site of PSII is not the rate-limiting step in the formation of photoactive thylakoid membranes.
authors.affiliation: Centre for Organelle Research, Faculty of Science and Technology, University of Stavanger, N-4036, Stavanger, Norway.|Department of Chemistry, Chemical Biological Centre, Umeå University, S-90187, Umeå, Sweden.
authors.forename: Dmitriy
authors.initials: D
authors.lastname: Shevela
authors.affiliation: Centre for Organelle Research, Faculty of Science and Technology, University of Stavanger, N-4036, Stavanger, Norway.
authors.forename: Janine
authors.initials: J
authors.lastname: Arnold
authors.affiliation: Centre for Organelle Research, Faculty of Science and Technology, University of Stavanger, N-4036, Stavanger, Norway.
authors.forename: Veronika
authors.initials: V
authors.lastname: Reisinger
authors.affiliation: Department of Chemistry, Chemical Biological Centre, Umeå University, S-90187, Umeå, Sweden.
authors.forename: Hans-Martin
authors.initials: HM
authors.lastname: Berends
authors.affiliation: Centre for Organelle Research, Faculty of Science and Technology, University of Stavanger, N-4036, Stavanger, Norway.
authors.forename: Karol
authors.initials: K
authors.lastname: Kmiec
authors.affiliation: Department of Chemistry, Chemical Biological Centre, Umeå University, S-90187, Umeå, Sweden.|PULSE Institute, SLAC National Accelerator Laboratory, Stanford University, Stanford, CA, 94305, USA.
authors.forename: Sergey
authors.initials: S
authors.lastname: Koroidov
authors.affiliation: Centre for Organelle Research, Faculty of Science and Technology, University of Stavanger, N-4036, Stavanger, Norway.
authors.forename: Ann Kristin
authors.initials: AK
authors.lastname: Bue
authors.affiliation: Department of Chemistry, Chemical Biological Centre, Umeå University, S-90187, Umeå, Sweden.
authors.forename: Johannes
authors.initials: J
authors.lastname: Messinger
authors.affiliation: Centre for Organelle Research, Faculty of Science and Technology, University of Stavanger, N-4036, Stavanger, Norway.
authors.forename: Lutz A
authors.initials: LA
authors.lastname: Eichacker
mesh_terms: D002734:Chlorophyll / Q000378:metabolism; D064527:Etiolation; D001467:Hordeum / Q000378:metabolism*; D001678:Organelle Biogenesis; D045332:Photosystem II Protein Complex / Q000378:metabolism*; D014867:Water / Q000378:metabolism*
chemical_list: D045332:Photosystem II Protein Complex; D014867:Water; D002734:Chlorophyll
keywords: chloroplast biogenesis; oxygen evolution; oxygen-evolving complex; photosystem II assembly