umu.sePublications
Change search
ReferencesLink to record
Permanent link

Direct link
The PsbY protein of Arabidopsis Photosystem II is important for the redox control of cytochrome b559
Umeå University, Faculty of Science and Technology, Department of Chemistry.
Umeå University, Faculty of Science and Technology, Department of Chemistry.
Show others and affiliations
2016 (English)In: Biochimica et Biophysica Acta - Bioenergetics, ISSN 0005-2728, E-ISSN 1879-2650, Vol. 1857, no 9, 1524-1533 p.Article in journal (Refereed) PublishedText
Abstract [en]

Abstract Photosystem II is a protein complex embedded in the thylakoid membrane of photosynthetic organisms and performs the light driven water oxidation into electrons and molecular oxygen that initiate the photosynthetic process. This important complex is composed of more than two dozen of intrinsic and peripheral subunits, of those half are low molecular mass proteins. PsbY is one of those low molecular mass proteins; this 4.7–4.9 kDa intrinsic protein seems not to bind any cofactors. Based on structural data from cyanobacterial and red algal Photosystem II PsbY is located closely or in direct contact with cytochrome b559. Cytb559 consists of two protein subunits (PsbE and PsbF) ligating a heme-group in-between them. While the exact function of this component in Photosystem II has not yet been clarified, a crucial role for assembly and photo-protection in prokaryotic complexes has been suggested. One unique feature of Cytb559 is its redox-heterogeneity, forming high, medium and low potential, however, neither origin nor mechanism are known. To reveal the function of PsbY within Photosystem II of Arabidopsis we have analysed PsbY knock-out plants and compared them to wild type and to complemented mutant lines. We show that in the absence of PsbY protein Cytb559 is only present in its oxidized, low potential form and plants depleted of PsbY were found to be more susceptible to photoinhibition.

Place, publisher, year, edition, pages
2016. Vol. 1857, no 9, 1524-1533 p.
Keyword [en]
Photosystem II, Thylakoid membrane, PsbY protein, Cytochrome b559
National Category
Chemical Sciences
Identifiers
URN: urn:nbn:se:umu:diva-124444DOI: 10.1016/j.bbabio.2016.05.004PubMedID: 27220875OAI: oai:DiVA.org:umu-124444DiVA: diva2:952081
Available from: 2016-08-11 Created: 2016-08-11 Last updated: 2016-09-22Bibliographically approved
In thesis
1. Characterization of auxiliary membrane proteins in the chloroplast of Arabidopsis thaliana
Open this publication in new window or tab >>Characterization of auxiliary membrane proteins in the chloroplast of Arabidopsis thaliana
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Alternative title[sv]
Karakterisering av membran-lokaliserade hjälparproteiner i kloroplasten hos växten backtrav
Abstract [en]

In nature, sessile plants have to adapt to their environment and to the never ending changes they are exposed to. They do so mainly by proteomic and metabolomic changes. In all cells, there are complex networks of auxiliary proteins that are responsible for quality control of all the cell's proteins. The auxiliary proteins are divided into chaperones and proteases, and these are further separated into different groups. Chaperones help other proteins in terms of stability and folding. In order for a protein to achieve its function, the three-dimensional structure has to be precise. A protease is a helper protein that is able to break peptide bonds in a process termed proteolysis. Chaperones and proteases can work independently, but sometimes the chaperone unfolds the substrate of the protease to ensure full degradation of the protein. In some cases, the chaperone and the protease functions are combined in one protein.

All proteins studied within this thesis are localized in the chloroplast, the organelle that originated from cyanobacteria, in which plants and algae convert the energy from sunlight into carbohydrates in the process called photosynthesis. Molecular oxygen is released as a by-product, and carbon dioxide is consumed. Photosystem II (PSII), one of the major protein complexes involved in photosynthesis, consists of more than 30 protein subunits, where around half of them are termed low molecular weight (LMW) proteins with a molecular size less than 10 kDa. In this thesis, data identifying one PSII LMW protein, PsbY, as a chaperone for the PSII subcomplex Cytochrome b559 are presented. In the absence of PsbY, Arabidopsis plants were more sensitive to photoinhibition, and the protective circular electron transport around PSII is completely blocked.

Data on members of the Filamentation temperature sensitive protein H (FtsH) protease family are also discussed, with a focus on FtsH11 and FtsHi1-i5. Members of the FtsH protease family carry a protease domain and a chaperone domain. Our data show that FtsH11 has an influence on the structure and function of chloroplasts of Arabidopsis plants grown under continuous light along with protein import into the same. FtsHi1-5 are five members with mutations within the proteolytic motif, most probably rendering them proteolytically inactive, hence they are referred to as ''inactive FtsH proteases''. Knock-out plants of the inactive members are embryo lethal, and knock-down plants grow slower than wild type, probably because of an affected level of plastid proteins at the translational level.

Place, publisher, year, edition, pages
Umeå: Umeå universitet, 2016. 52 p.
Keyword
Arabidopsis, chaperone, chloroplast, Cytochrome b559, FtsH, membrane proteins, photosynthesis, Photosystem II, protease, PsbY., Arabidopsis, chaperone, Cytochrome b559, fotosyntes, fotosystem II, FtsH, kloroplast, membranprotein, proteas, PsbY.
National Category
Biochemistry and Molecular Biology Plant Biotechnology
Research subject
Biochemistry
Identifiers
urn:nbn:se:umu:diva-125819 (URN)978-91-7601-480-6 (ISBN)
Public defence
2016-10-10, N450, Naturvetarhuset, Umeå, 10:00 (English)
Opponent
Supervisors
Funder
Swedish Energy Agency, 2012-005889​
Note

Avhandlingen är skriven på engelska, men innehåller också en enkel sammanfattning på svenska. 

Available from: 2016-09-26 Created: 2016-09-19 Last updated: 2016-09-23Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full textPubMed

Search in DiVA

By author/editor
von Sydow, LottaFunk, ChristianeSchröder, Wolfgang P.
By organisation
Department of Chemistry
In the same journal
Biochimica et Biophysica Acta - Bioenergetics
Chemical Sciences

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 41 hits
ReferencesLink to record
Permanent link

Direct link