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The Periplasmic Loop Provides Stability to the Open State of the CorA Magnesium Channel
Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
2012 (English)In: Journal of Biological Chemistry, ISSN 0021-9258, E-ISSN 1083-351X, Vol. 287, no 33, 27547-27555 p.Article in journal (Refereed) Published
Abstract [en]

Crystal structures of the CorA Mg2+ channel have suggested that metal binding in the cytoplasmic domain stabilizes the pentamer in a closed conformation. The open metal free state of the channel is, however, still structurally uncharacterized. Here, we have attempted to map conformational states of CorA from Thermotoga maritima by determining which residues support the pentameric structure in the presence or absence of Mg2+. We find that when Mg2+ is present, the pentamer is stabilized by the putative gating sites (M1/M2) in the cytoplasmic domain. Strikingly however, we find that the conserved and functionally important periplasmic loop is vital for the integrity of the pentamer when Mg2+ is absent from the M1/M2 sites. Thus, although the periplasmic loops were largely disordered in the x-ray structures of the closed channel, our data suggests a prominent role for the loops in stabilizing the open conformation of the CorA channels.

Place, publisher, year, edition, pages
2012. Vol. 287, no 33, 27547-27555 p.
National Category
Biochemistry and Molecular Biology
Research subject
Biochemistry
Identifiers
URN: urn:nbn:se:su:diva-82951DOI: 10.1074/jbc.M112.371484ISI: 000307840700030OAI: oai:DiVA.org:su-82951DiVA: diva2:576920
Note

AuthorCount:3;

Available from: 2012-12-14 Created: 2012-12-03 Last updated: 2017-12-06Bibliographically approved
In thesis
1. The social life of a membrane protein; It's complex
Open this publication in new window or tab >>The social life of a membrane protein; It's complex
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Membrane proteins are key players in many biological processes. Since most membrane proteins are assembled into oligomeric complexes it is important to understand how they interact with each other. Unfortunately however, the assembly process (i.e. their social life) remains poorly understood. In the work presented in this thesis I have investigated when and how membrane proteins assemble with each other and their cofactors to form functional units. We have shown that that cofactor insertion in the hetero-tetrameric cytochrome bo3 occurs at an early state in the assembly process. We also found that the pentameric CorA magnesium ion channel is stabilised by different interactions depending on the magnesium ion concentration in the cell. These studies indicate that the assembly of a functional unit is a dynamic process, which is a result of many different forces. By studying the assembly of membrane proteins we have obtained a deeper insight into their function, which cannot be explained by static crystal structures.

Place, publisher, year, edition, pages
Stockholm: Department of Biochemistry and Biophysics, Stockholm University, 2013. 52 p.
Keyword
membrane proteins, assembly, cofactors, magnesium, Escherichia coli
National Category
Biochemistry and Molecular Biology
Research subject
Biochemistry
Identifiers
urn:nbn:se:su:diva-88597 (URN)978-91-7447-671-2 (ISBN)
Public defence
2013-05-03, Magnélisalen, Kemiska övningslaboratoriet, Svante Arrhenius väg 16 B, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 2: Manuscript.

Available from: 2013-04-11 Created: 2013-03-21 Last updated: 2013-03-29Bibliographically approved

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