scholarly journals A general mechanism for drug promiscuity: Studies with amiodarone and other antiarrhythmics

2015 ◽  
Vol 146 (6) ◽  
pp. 463-475 ◽  
Author(s):  
Radda Rusinova ◽  
Roger E. Koeppe ◽  
Olaf S. Andersen
Keyword(s):  
Membrane Proteins ◽  
Lipid Bilayer ◽  
Protein Function ◽  
Single Channel ◽  
General Mechanism ◽  
Antiarrhythmic Agents ◽  
Diverse Range ◽  
Lipid Mixtures ◽  
Membrane Protein Function

Amiodarone is a widely prescribed antiarrhythmic drug used to treat the most prevalent type of arrhythmia, atrial fibrillation (AF). At therapeutic concentrations, amiodarone alters the function of many diverse membrane proteins, which results in complex therapeutic and toxicity profiles. Other antiarrhythmics, such as dronedarone, similarly alter the function of multiple membrane proteins, suggesting that a multipronged mechanism may be beneficial for treating AF, but raising questions about how these antiarrhythmics regulate a diverse range of membrane proteins at similar concentrations. One possible mechanism is that these molecules regulate membrane protein function by altering the common environment provided by the host lipid bilayer. We took advantage of the gramicidin (gA) channels’ sensitivity to changes in bilayer properties to determine whether commonly used antiarrhythmics—amiodarone, dronedarone, propranolol, and pindolol, whose pharmacological modes of action range from multi-target to specific—perturb lipid bilayer properties at therapeutic concentrations. Using a gA-based fluorescence assay, we found that amiodarone and dronedarone are potent bilayer modifiers at therapeutic concentrations; propranolol alters bilayer properties only at supratherapeutic concentration, and pindolol has little effect. Using single-channel electrophysiology, we found that amiodarone and dronedarone, but not propranolol or pindolol, increase bilayer elasticity. The overlap between therapeutic and bilayer-altering concentrations, which is observed also using plasma membrane–like lipid mixtures, underscores the need to explore the role of the bilayer in therapeutic as well as toxic effects of antiarrhythmic agents.

scholarly journals Assessing the Role of Lipids in the Molecular Mechanism of Membrane Proteins

2021 ◽  
Vol 22 (14) ◽  
pp. 7267
Author(s):  
Léni Jodaitis ◽  
Thomas van Oene ◽  
Chloé Martens
Keyword(s):  
Membrane Proteins ◽  
Molecular Mechanism ◽  
Protein Interactions ◽  
Protein Function ◽  
Biological Membrane ◽  
Allosteric Coupling ◽  
Lipid Protein Interactions ◽  
Experimental Challenge ◽  
Membrane Protein Function

Membrane proteins have evolved to work optimally within the complex environment of the biological membrane. Consequently, interactions with surrounding lipids are part of their molecular mechanism. Yet, the identification of lipid–protein interactions and the assessment of their molecular role is an experimental challenge. Recently, biophysical approaches have emerged that are compatible with the study of membrane proteins in an environment closer to the biological membrane. These novel approaches revealed specific mechanisms of regulation of membrane protein function. Lipids have been shown to play a role in oligomerization, conformational transitions or allosteric coupling. In this review, we summarize the recent biophysical approaches, or combination thereof, that allow to decipher the role of lipid–protein interactions in the mechanism of membrane proteins.

Mechanisms underlying drug-mediated regulation of membrane protein function

2021 ◽  
Vol 118 (46) ◽  
pp. e2113229118
Author(s):  
Radda Rusinova ◽  
Changhao He ◽  
Olaf S. Andersen
Keyword(s):  
Membrane Proteins ◽  
Membrane Protein ◽  
Lipid Bilayer ◽  
Conformational Changes ◽  
Protein Function ◽  
Nonspecific Binding ◽  
Drug Induced ◽  
Protein Conformational Changes ◽  
Potassium Channel Kcsa ◽  
Membrane Protein Function

The hydrophobic coupling between membrane proteins and their host lipid bilayer provides a mechanism by which bilayer-modifying drugs may alter protein function. Drug regulation of membrane protein function thus may be mediated by both direct interactions with the protein and drug-induced alterations of bilayer properties, in which the latter will alter the energetics of protein conformational changes. To tease apart these mechanisms, we examine how the prototypical, proton-gated bacterial potassium channel KcsA is regulated by bilayer-modifying drugs using a fluorescence-based approach to quantify changes in both KcsA function and lipid bilayer properties (using gramicidin channels as probes). All tested drugs inhibited KcsA activity, and the changes in the different gating steps varied with bilayer thickness, suggesting a coupling to the bilayer. Examining the correlations between changes in KcsA gating steps and bilayer properties reveals that drug-induced regulation of membrane protein function indeed involves bilayer-mediated mechanisms. Both direct, either specific or nonspecific, binding and bilayer-mediated mechanisms therefore are likely to be important whenever there is overlap between the concentration ranges at which a drug alters membrane protein function and bilayer properties. Because changes in bilayer properties will impact many diverse membrane proteins, they may cause indiscriminate changes in protein function.

Insights into biological functions across species: examining the role of Rab proteins in YIP1 family function

2005 ◽  
Vol 33 (4) ◽  
pp. 614-618 ◽  
Author(s):  
C.Z. Chen ◽  
R.N. Collins
Keyword(s):  
Membrane Proteins ◽  
Protein Function ◽  
Evolutionary Conservation ◽  
Biological Role ◽  
Rab Proteins ◽  
Biological Functions ◽  
Human Homologue ◽  
Family Function ◽  
Evolutionarily Conserved

The YIP1 family comprises an evolutionarily conserved group of membrane proteins, which share the ability to bind di-prenylated Rab proteins. The biochemical capability of YIP1 family proteins suggests a possible role in the cycle of physical localization of Rab proteins between their cognate membranes and the cytosol. YIP1 is essential for viability in yeast and a deletion of YIP1 can be rescued with the human homologue YIP1A. We have made use of this evolutionary conservation of function to generate a series of mutant alleles of YIP1 to investigate the biological role of Yip1p. Our findings indicate evidence for the participation of Yip1p in both Rab and COPII protein function; at present, we are not able to distinguish between the models that these roles represent, i.e. independent or dependent activities of Yip1p.

scholarly journals Non-vesicular transfer of membrane proteins from nanoparticles to lipid bilayers

2011 ◽  
Vol 137 (2) ◽  
pp. 217-223 ◽  
Author(s):  
Sourabh Banerjee ◽  
Crina M. Nimigean
Keyword(s):  
Membrane Proteins ◽  
Lipid Bilayer ◽  
Lipid Bilayers ◽  
Single Molecule ◽  
Lipid Membranes ◽  
Single Channel ◽  
Black Lipid Membranes ◽  
Potassium Channel Kcsa ◽  
Lipid Environment ◽  
Biochemical Preparation

Discoidal lipoproteins are a novel class of nanoparticles for studying membrane proteins (MPs) in a soluble, native lipid environment, using assays that have not been traditionally applied to transmembrane proteins. Here, we report the successful delivery of an ion channel from these particles, called nanoscale apolipoprotein-bound bilayers (NABBs), to a distinct, continuous lipid bilayer that will allow both ensemble assays, made possible by the soluble NABB platform, and single-molecule assays, to be performed from the same biochemical preparation. We optimized the incorporation and verified the homogeneity of NABBs containing a prototypical potassium channel, KcsA. We also evaluated the transfer of KcsA from the NABBs to lipid bilayers using single-channel electrophysiology and found that the functional properties of the channel remained intact. NABBs containing KcsA were stable, homogeneous, and able to spontaneously deliver the channel to black lipid membranes without measurably affecting the electrical properties of the bilayer. Our results are the first to demonstrate the transfer of a MP from NABBs to a different lipid bilayer without involving vesicle fusion.

scholarly journals Lipid bilayer regulation of membrane protein function: gramicidin channels as molecular force probes

2009 ◽  
Vol 7 (44) ◽  
pp. 373-395 ◽  
Author(s):  
Jens A. Lundbæk ◽  
Shemille A. Collingwood ◽  
Helgi I. Ingólfsson ◽  
Ruchi Kapoor ◽  
Olaf S. Andersen
Keyword(s):  
Membrane Protein ◽  
Physical Properties ◽  
Lipid Bilayer ◽  
Protein Function ◽  
Elastic Moduli ◽  
Model Systems ◽  
Energetic Cost ◽  
Molecular Force ◽  
Membrane Protein Function ◽  
Force Probes

Membrane protein function is regulated by the host lipid bilayer composition. This regulation may depend on specific chemical interactions between proteins and individual molecules in the bilayer, as well as on non-specific interactions between proteins and the bilayer behaving as a physical entity with collective physical properties (e.g. thickness, intrinsic monolayer curvature or elastic moduli). Studies in physico-chemical model systems have demonstrated that changes in bilayer physical properties can regulate membrane protein function by altering the energetic cost of the bilayer deformation associated with a protein conformational change. This type of regulation is well characterized, and its mechanistic elucidation is an interdisciplinary field bordering on physics, chemistry and biology. Changes in lipid composition that alter bilayer physical properties (including cholesterol, polyunsaturated fatty acids, other lipid metabolites and amphiphiles) regulate a wide range of membrane proteins in a seemingly non-specific manner. The commonality of the changes in protein function suggests an underlying physical mechanism, and recent studies show that at least some of the changes are caused by altered bilayer physical properties. This advance is because of the introduction of new tools for studying lipid bilayer regulation of protein function. The present review provides an introduction to the regulation of membrane protein function by the bilayer physical properties. We further describe the use of gramicidin channels as molecular force probes for studying this mechanism, with a unique ability to discriminate between consequences of changes in monolayer curvature and bilayer elastic moduli.

scholarly journals DNA-Encircled Lipid Bilayers

2018 ◽  
Author(s):  
Katarina Iric ◽  
Madhumalar Subramanian ◽  
Jana Oertel ◽  
Nayan P. Agarwal ◽  
Michael Matthies ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Lipid Bilayer ◽  
Lipid Bilayers ◽  
Protein Interactions ◽  
Protein Function ◽  
Dna Nanotechnology ◽  
Lipid Vesicles ◽  
Associated Proteins

ABSTRACTLipid bilayers and lipid-associated proteins play a crucial role in biology. As in vivo studies and manipulation are inherently difficult, several membrane-mimetic systems have been developed to enable investigation of lipidic phases, lipid-protein interactions, membrane protein function and membrane structure in vitro. Controlling the size and shape, or site-specific functionalization is, however, difficult to achieve with established membrane mimetics based on membrane scaffolding proteins, polymers or peptides. In this work, we describe a route to leverage the unique programmability of DNA nanotechnology and create DNA-encircled bilayers (DEBs), which are made of multiple copies of an alkylated oligonucleotide hybridized to a single-stranded minicircle. To stabilize the hydrophobic rim of the lipid bilayer, and to prevent formation of lipid vesicles, we introduced up to 2 alkyl chains per helical that point to the inside of the toroidal DNA ring and interact with the hydrophobic side chains of the encapsulated lipid bilayer. The DEB approach described herein provides unprecedented control of size, and allows the orthogonal functionalizations and arrangement of engineered membrane nanoparticles and will become a valuable tool for biophysical investigation of lipid phases and lipid-associated proteins and complexes including structure determination of membrane proteins and pharmacological screenings of membrane proteins.

scholarly journals EncoMPASS: an Encyclopedia of Membrane Proteins Analyzed by Structure and Symmetry

2018 ◽  
Author(s):  
Antoniya A. Aleksandrova ◽  
Edoardo Sarti ◽  
Lucy R. Forrest
Keyword(s):  
Protein Structure ◽  
Membrane Proteins ◽  
Protein Function ◽  
Sequence Similarity ◽  
Protein Structure Determination ◽  
List Type ◽  
Online Tools ◽  
Structural Relationships ◽  
Step Procedure ◽  
Membrane Protein Function

SummaryProtein structure determination and prediction, active site detection, and protein sequence alignment techniques all exploit information about protein structure and structural relationships. For membrane proteins, however, there is no agreement among available online tools for highlighting and mapping such structural similarities. Moreover, no available resource provides a systematic overview of quaternary and internal symmetries, and their orientation with respect to the membrane, despite the fact that these properties can provide key insights into membrane protein function. To address these issues, we created theEncyclopediaofMembraneProteinsAnalyzed byStructure and Symmetry (EncoMPASS), a database for relating integral membrane proteins of known structure from the points of view of sequence, structure, and symmetry. EncoMPASS is accessible athttps://encompass.ninds.nih.govand its contents can be easily downloaded. This allows the user not only to focus on specific systems, but also to study general properties of the structure and evolution of membrane proteins.Highlights-EncoMPASS relates and analyzes known structures of membrane proteins-Structure and sequence similarity is assessed through alignments and topology considerations, not clustering-Symmetry is detected based on CE-Symm and SymD using a multi-step procedure

scholarly journals The Role of Phosphatidylethanolamine Adducts in Modification of the Activity of Membrane Proteins under Oxidative Stress

Molecules ◽  
2019 ◽  
Vol 24 (24) ◽  
pp. 4545 ◽  
Author(s):  
Elena E. Pohl ◽  
Olga Jovanovic
Keyword(s):  
Oxidative Stress ◽  
Membrane Proteins ◽  
Protein Function ◽  
Lipid Membrane ◽  
Membrane Lipids ◽  
Short Review ◽  
Membrane Properties ◽  
Complex Nature ◽  
Reactive Aldehydes

Reactive oxygen species (ROS) and their derivatives, reactive aldehydes (RAs), have been implicated in the pathogenesis of many diseases, including metabolic, cardiovascular, and inflammatory disease. Understanding how RAs can modify the function of membrane proteins is critical for the design of therapeutic approaches in the above-mentioned pathologies. Over the last few decades, direct interactions of RA with proteins have been extensively studied. Yet, few studies have been performed on the modifications of membrane lipids arising from the interaction of RAs with the lipid amino group that leads to the formation of adducts. It is even less well understood how various multiple adducts affect the properties of the lipid membrane and those of embedded membrane proteins. In this short review, we discuss a crucial role of phosphatidylethanolamine (PE) and PE-derived adducts as mediators of RA effects on membrane proteins. We propose potential PE-mediated mechanisms that explain the modulation of membrane properties and the functions of membrane transporters, channels, receptors, and enzymes. We aim to highlight this new area of research and to encourage a more nuanced investigation of the complex nature of the new lipid-mediated mechanism in the modification of membrane protein function under oxidative stress.

scholarly journals Exceptional Flexibility in the Sequence Requirements for Coronavirus Small Envelope Protein Function

2006 ◽  
Vol 81 (5) ◽  
pp. 2249-2262 ◽  
Author(s):  
Lili Kuo ◽  
Kelley R. Hurst ◽  
Paul S. Masters
Keyword(s):  
Envelope Protein ◽  
Protein Function ◽  
Hepatitis Virus ◽  
Amino Acid Sequences ◽  
Transmissible Gastroenteritis Virus ◽  
Diverse Range ◽  
E Gene ◽  
Cellular Expression ◽  
E Protein

ABSTRACT The small envelope protein (E) plays a role of central importance in the assembly of coronaviruses. This was initially established by studies demonstrating that cellular expression of only E protein and the membrane protein (M) was necessary and sufficient for the generation and release of virus-like particles. To investigate the role of E protein in the whole virus, we previously generated E gene mutants of mouse hepatitis virus (MHV) that were defective in viral growth and produced aberrantly assembled virions. Surprisingly, however, we were also able to isolate a viable MHV mutant (ΔE) in which the entire E gene, as well as the nonessential upstream genes 4 and 5a, were deleted. We have now constructed an E knockout mutant that confirms that the highly defective phenotype of the ΔE mutant is due to loss of the E gene. Additionally, we have created substitution mutants in which the MHV E gene was replaced by heterologous E genes from viruses spanning all three groups of the coronavirus family. Group 2 and 3 E proteins were readily exchangeable for that of MHV. However, the E protein of a group 1 coronavirus, transmissible gastroenteritis virus, became functional in MHV only after acquisition of particular mutations. Our results show that proteins encompassing a remarkably diverse range of primary amino acid sequences can provide E protein function in MHV. These findings suggest that E protein facilitates viral assembly in a manner that does not require E protein to make sequence-specific contacts with M protein.

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