title: ALB3 Insertase Mediates Cytochrome b6Co-translational Import into the Thylakoid Membrane.
abstract: The cytochrome b6f complex occupies an electrochemically central position in the electron-transport chain bridging the photosynthetic reaction center of PS I and PS II. In plants, the subunits of these thylakoid membrane protein complexes are both chloroplast and nuclear encoded. How the chloroplast-encoded subunits of multi-spanning cytochrome b6are targeted and inserted into the thylakoid membrane is not fully understood. Experimental approaches to evaluate the cytochrome b6import mechanism in vivo have been limited to bacterial membranes and were not a part of the chloroplast environment. To evaluate the mechanism governing cytochrome b6integration in vivo, we performed a comparative analysis of both native and synthetic cytochrome b6insertion into purified thylakoids. Using biophysical and biochemical methods, we show that cytochrome b6insertion into the thylakoid membrane is a non-spontaneous co-translational process that involves ALB3 insertase. Furthermore, we provided evidence that CSP41 (chloroplast stem-loop-binding protein of 41 kDa) interacts with RNC-cytochrome b6complexes, and may be involved in cytochrome b6(petB) transcript stabilization or processing.
authors.affiliation: Laboratory of Chemical Biology, Faculty of Biotechnology, University of Wrocław, Wrocław Poland.
authors.forename: Jarosław
authors.initials: J
authors.lastname: Króliczewski
authors.affiliation: Amplicon Sp. z o. o., Wrocław, Poland.|Faculty of Biotechnology, University of Wrocław, Wrocław, Poland.
authors.forename: Małgorzata
authors.initials: M
authors.lastname: Piskozub
authors.affiliation: Department of Biology and Pharmaceutical Botany, Medical University of Gdansk, Gdansk, Poland.
authors.forename: Rafał
authors.initials: R
authors.lastname: Bartoszewski
authors.affiliation: Department of Animal Physiology and Biostructure, Faculty of Veterinary Medicine, Wrocław University of Environmental and Life Sciences, Wrocław, Poland.
authors.forename: Bożena
authors.initials: B
authors.lastname: Króliczewska
mesh_terms: D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism; D045347:Cytochromes b6 / Q000235:genetics / Q000378:metabolism*; D018532:Pisum sativum / Q000235:genetics / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D021381:Protein Transport / Q000502:physiology; D020524:Thylakoids / Q000235:genetics / Q000378:metabolism*
chemical_list: D002352:Carrier Proteins; D045347:Cytochromes b6; D010940:Plant Proteins