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Interaction between soluble and membrane-embedded potassium channel peptides monitored by Fourier transform infrared spectroscopy.

Abbott, GW; Ramesh, B; Srai, SK; (2012) Interaction between soluble and membrane-embedded potassium channel peptides monitored by Fourier transform infrared spectroscopy. PLOS One , 7 (11) , Article e49070. 10.1371/journal.pone.0049070. Green open access

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Abstract

Recent studies have explored the utility of Fourier transform infrared spectroscopy (FTIR) in dynamic monitoring of soluble protein-protein interactions. Here, we investigated the applicability of FTIR to detect interaction between synthetic soluble and phospholipid-embedded peptides corresponding to, respectively, a voltage-gated potassium (Kv) channel inactivation domain (ID) and S4-S6 of the Shaker Kv channel (KV1; including the S4-S5 linker "pre-inactivation" ID binding site). KV1 was predominantly α-helical at 30°C when incorporated into dimyristoyl-l-α-phosphatidylcholine (DMPC) bilayers. Cooling to induce a shift in DMPC from liquid crystalline to gel phase reversibly decreased KV1 helicity, and was previously shown to partially extrude a synthetic S4 peptide. While no interaction was detected in liquid crystalline DMPC, upon cooling to induce the DMPC gel phase a reversible amide I peak (1633 cm(-1)) consistent with novel hydrogen bond formation was detected. This spectral shift was not observed for KV1 in the absence of ID (or vice versa), nor when the non-inactivating mutant V7E ID was applied to KV1 under similar conditions. Alteration of salt or redox conditions affected KV1-ID hydrogen bonding in a manner suggesting electrostatic KV1-ID interaction favored by a hairpin conformation for the ID and requiring extrusion of one or more KV1 domains from DMPC, consistent with ID binding to S4-S5. These findings support the utility of FTIR in detecting reversible interactions between soluble and membrane-embedded proteins, with lipid state-sensitivity of the conformation of the latter facilitating control of the interaction.

Type: Article
Title: Interaction between soluble and membrane-embedded potassium channel peptides monitored by Fourier transform infrared spectroscopy.
Location: United States
Open access status: An open access version is available from UCL Discovery
DOI: 10.1371/journal.pone.0049070
Publisher version: http://dx.doi.org/10.1371/journal.pone.0049070
Language: English
Additional information: © 2012 Abbott et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. The authors are grateful for financial support from the Peter Samuels Royal Free Fund and University of California, Irvine setup funds. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
UCL classification: UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences > Div of Biosciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences > Div of Biosciences > Structural and Molecular Biology
URI: http://discovery.ucl.ac.uk/id/eprint/1372241
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