umu.sePublications
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
The lumenal pentapeptide repeat proteins TL15 and TL20.3 are novel chaperone-like proteins in the chloroplast lumen of higher plants
Umeå University, Faculty of Science and Technology, Department of Chemistry. (Wolfgang Schröder)
Umeå University, Faculty of Science and Technology, Department of Chemistry.
Umeå University, Faculty of Science and Technology, Department of Chemistry.
Umeå University, Faculty of Science and Technology, Department of Chemistry.
Show others and affiliations
(English)Manuscript (preprint) (Other academic)
Abstract [en]

In the thylakoid lumen of Arabidopsis thaliana, three pentapeptide repeat family proteins of unknown function are localized. Pentapeptide repeat proteins (PRP) are comprised of at least eight tandem repeats of five amino acids of the consensus sequence A(D/N)LXX, which fold into a quadrilateral beta helix structure. Here we have solved the crystal structure of the mature form of the lumenal PRP protein TL15 to 1.3 Å resolution. TL15 is comprised of a main pentapeptide domain, consisting of a total of 19 pentapeptide repeats which form five turns of a beta helix, and a C-terminal alpha helix domain consisting of two alpha helices. The alpha helices form a ‘cap’ at the C-terminal end of the beta helix and are connected by a disulphide bond between the conserved cysteine residues C122 and C142. Furthermore we show that the lumenal PRPs TL15 and TL20.3 can assist in refolding of a chemically denatured substrate in vitro, indicating foldase chaperone activity. The three lumenal PRPs have been previously identified as targets of thioredoxin, and interestingly we observed a greatly increased chaperone activity of TL15 and TL20.3 after reduction of their disulphide bonds. Our results provide the high resolution crystal structure of the TL15 protein and our analysis of chaperone activity suggests that TL15 and TL20.3 may constitute a novel type of redox-regulated molecular chaperones in the chloroplast lumen of higher plants.

Keyword [en]
Photosynthesis, Chloroplast lumen
National Category
Biochemistry and Molecular Biology
Research subject
Biochemistry
Identifiers
URN: urn:nbn:se:umu:diva-58364OAI: oai:DiVA.org:umu-58364DiVA: diva2:548010
Available from: 2012-08-29 Created: 2012-08-29 Last updated: 2012-08-30Bibliographically approved
In thesis
1. The chloroplast lumen: New insights into thiol redox regulation and functions of lumenal proteins
Open this publication in new window or tab >>The chloroplast lumen: New insights into thiol redox regulation and functions of lumenal proteins
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In higher plants oxygenic photosynthesis primarily takes place in the chloroplasts of leaves. Within the chloroplasts is an intricate membrane system, the thylakoid membrane, which is the site of light harvesting and photosynthetic electron transport. Enclosed by this membrane is the lumen space, which initially was believed to only contain a few proteins, but now is known to house a distinct set of >50 proteins, many for which there is still no proposed function. The work presented in this thesis is focused on understanding the functions of the proteins in the lumen space. Using proteomic methods, we investigated first the regulation of lumenal proteins by light and secondly by dithiol-disulphide exchange, mediated by the disulphide reductase protein thioredoxin. We furthermore performed structural and functional studies of the lumenal pentapeptide repeat proteins and of the PsbP-domain protein PPD6. When studying the diurnal expression pattern of the lumen proteins, using difference gel electrophoresis, we observed an increased abundance of fifteen lumen protein in light-adapted Arabidopsis thaliana plants. Among these proteins were subunits of the oxygen evolving complex, plastocyanin and proteins of unknown function. In our analysis of putative lumenal targets of thioredoxin, we identified nineteen proteins, constituting more than 40 % of the lumen proteins observable by our methods. A subset of these putative target proteins were selected for further studies, including structure determination by x-ray crystallography. The crystal structure of the pentapeptide repeat protein TL15 was solved to 1.3 Å resolution and further biochemical characterization suggested that it may function as a novel type of redox regulated molecular chaperone in the lumen. PPD6, a member of the PsbP-family of proteins, which is unique in that it possesses a conserved disulphide bond not found in any other PsbP-family protein, was also expressed, purified and crystallized. A preliminary x-ray analysis suggests that PPD6 exists as a dimer in the crystalline state and binds zinc ions. The high representation of targets of thioredoxin among the lumen proteins, along with the characterization of the pentapeptide repeat protein family, implies that dithiol-disulphide exchange reactions play an important role in the thylakoid lumen of higher plants, regulating processes such as photoprotection, protein turnover and protein folding.

Place, publisher, year, edition, pages
Umeå: Umeå universitet, 2012. 65 p.
Keyword
Photosynthesis, thylakoid lumen, thioredoxin, pentapeptide repeat, proteomics
National Category
Biochemistry and Molecular Biology
Research subject
Biochemistry
Identifiers
urn:nbn:se:umu:diva-58423 (URN)978-91-7459-467-6 (ISBN)
Public defence
2012-09-21, KBC huset, KB3B1, Umeå Universitet, Umeå, 09:00 (English)
Opponent
Supervisors
Available from: 2012-08-31 Created: 2012-08-29 Last updated: 2012-08-30Bibliographically approved

Open Access in DiVA

No full text

Search in DiVA

By author/editor
Hall, Michaelvon Sydow, LottaStorm, PatrikSauer, UweKieselbach, ThomasSchröder, Wolfgang
By organisation
Department of ChemistryUmeå Plant Science Centre (UPSC)
Biochemistry and Molecular Biology

Search outside of DiVA

GoogleGoogle Scholar

urn-nbn

Altmetric score

urn-nbn
Total: 208 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf