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Structural characterization of AS1-membrane interactions from a subset of HAMP domains
Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
2011 (English)In: Biochimica et Biophysica Acta - Biomembranes, ISSN 0005-2736, E-ISSN 1879-2642, Vol. 1808, no 10, 2403-2412 p.Article in journal (Refereed) Published
Abstract [en]

HAMP domains convert an extracellular sensory input into an intracellular signaling response in a wide variety of membrane-embedded bacterial proteins. These domains are almost invariably found adjacent to the inner leaflet of the cell membrane. We therefore examined the interaction of peptides corresponding to either AS1 or AS2 of four different, well-characterized HAMP domains with several membrane model systems. The proteins included an Archaeoglobus fulgidus protein (Af1503), the Escherichia coli osmosensor EnvZ(Ec), the E. coli nitrate/nitrite sensor NarX(Ec), and the aspartate chemoreceptor of E. coli (Tar(Ec)). Far-UV CD and NMR spectroscopy were used to monitor the induction of secondary structure upon association with neutral or acidic large unilamellar vesicles (LUVs) and bicelles. We observed significant increases in alpha-helicity within AS1 from NarX(Ec) and Tar(Ec) but not in AS1 from the other proteins. To characterize these interactions further, we determined the solution structure of AS1 from Tar(Ec) associated with acidic bicelles. The bulk of AS1 formed an amphipathic alpha-helix, whereas the N-terminal control cable, the region between TM2 and AS1, remained unstructured. We observed that the conserved prolyl residue found in AS1 of many membrane-adjacent HAMP domains defined the boundary between the unstructured and helical regions. In addition, two positively charged residues that flank the hydrophobic surface of AS1 are thought to facilitate electrostatic interactions with the membrane. We interpret these results within the context of the helix-interaction model for HAMP signaling and propose roles for AS1-membrane interactions during the membrane assembly and transmembrane communication of HAMP-containing receptors.

Place, publisher, year, edition, pages
2011. Vol. 1808, no 10, 2403-2412 p.
Keyword [en]
HAMP domain, Signal transduction, Transmembrane communication, AS1-membrane interactions, Helix-interaction model
National Category
Biophysics
Research subject
Biophysics
Identifiers
URN: urn:nbn:se:su:diva-66515DOI: 10.1016/j.bbamem.2011.06.018ISI: 000294982000008OAI: oai:DiVA.org:su-66515DiVA: diva2:469855
Funder
Swedish Research Council, 621-2011-5964
Note

authorCount :3

Available from: 2011-12-27 Created: 2011-12-20 Last updated: 2017-12-08Bibliographically approved
In thesis
1. Membrane Induced Structure in Transmembrane Signaling Proteins and Peptides: Peptide–Lipid Interactions Studied by Spectroscopic Methods
Open this publication in new window or tab >>Membrane Induced Structure in Transmembrane Signaling Proteins and Peptides: Peptide–Lipid Interactions Studied by Spectroscopic Methods
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Biological membranes, defining the boundary of cells and eukaryotic organelles, are mainly composed of lipids and membrane proteins. Interactions between these lipids and proteins are needed to preserve the tight seal of the membrane, but also to induce structure for proper function in many membrane proteins. In this thesis, interactions between three different kinds of peptides, i.e. small proteins, and model membranes are studied by spectroscopic methods.

First, the membrane interaction of two paddle domains, KvAPp, from the voltage-gated potassium channel KvAP from Aeropyrum pernix, and HsapBKp, from the human, large conductance, calcium-activated potassium channel HsapBK, was studied (paper I and II). In paper I, a high-resolution solution NMR structure of HsapBKp in detergent micelles is presented revealing a helix-turn-helix motif. Small structural differences between HsapBKp and KvAPp, positioning the arginines differently, are presented. These structural differences may explain why BK channels are weakly voltage-gated. In paper II, it is shown that HsapBKp perturbs the membrane more than KvAPp and that the membrane perturbation is related to β-structure and to dynamics in the turn in the helix-turn-helix motif.

Second, the membrane interaction of HAMP domains modulating transmission in prokaryotic transmembrane signaling was studied (paper III). Based on the membrane interaction of the AS1 segments of the HAMP domains, two groups were identified: one strongly membrane interacting and one weakly membrane interacting. The two groups are suggested to use different signaling mechanisms.

Third, nonspecific binding of proinsulin C-peptide, the linker peptide connecting chain A and B in insulin, to model membranes was studied (paper IV). The study revealed that C-peptide binds to a model membrane at low pH, but the membrane induces no large structural rearrangements of the peptide. 

Place, publisher, year, edition, pages
Stockholm: Department of Biochemistry and Biophysics, Stockholm University, 2012. 59 p.
Keyword
peptide-lipid interaction, paddle domain, voltage gating, voltage sensor domain, micelle, phospholipid bicelle, solution structure, HAMP domain, nuclear magnetic resonance spectroscopy, circular dichroism spectroscopy, nonspecific interaction
National Category
Biophysics
Research subject
Biophysics
Identifiers
urn:nbn:se:su:diva-79051 (URN)978-91-7447-564-7 (ISBN)
Public defence
2012-09-28, Magnélisalen, Kemiska övningslaboratoriet, Svante Arrhenius väg 16 B, Stockholm, 10:00 (English)
Opponent
Supervisors
Available from: 2012-09-06 Created: 2012-08-24 Last updated: 2012-08-29Bibliographically approved

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Unnerståle, SofiaMäler, Lena
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