scholarly journals Membrane proteins: always an insoluble problem?

2016 ◽  
Vol 44 (3) ◽  
pp. 790-795 ◽  
Author(s):  
Andrea E. Rawlings
Keyword(s):  
Membrane Proteins ◽  
Lipid Membranes ◽  
Drug Targets ◽  
Functional Characterization ◽  
Water Soluble ◽  
High Yield ◽  
Cellular Processes ◽  
Native Sequence ◽  
Protein Research ◽  
New Methodologies

Membrane proteins play crucial roles in cellular processes and are often important pharmacological drug targets. The hydrophobic properties of these proteins make full structural and functional characterization challenging because of the need to use detergents or other solubilizing agents when extracting them from their native lipid membranes. To aid membrane protein research, new methodologies are required to allow these proteins to be expressed and purified cheaply, easily, in high yield and to provide water soluble proteins for subsequent study. This mini review focuses on the relatively new area of water soluble membrane proteins and in particular two innovative approaches: the redesign of membrane proteins to yield water soluble variants and how adding solubilizing fusion proteins can help to overcome these challenges. This review also looks at naturally occurring membrane proteins, which are able to exist as stable, functional, water soluble assemblies with no alteration to their native sequence.

A Novel Reconstitution Method for Inducing the Formation of Regular 2-Dimensional Arrays of Membrane Proteins and Lipids

1988 ◽  
Vol 46 ◽  
pp. 152-153 ◽  
Author(s):  
A. Engel ◽  
A. Holzenburg ◽  
K. Stauffer ◽  
J. Rosenbusch ◽  
U. Aebi
Keyword(s):  
Membrane Proteins ◽  
Flow Rate ◽  
Lipid Membranes ◽  
Functional Characterization ◽  
Dimensional Structure ◽  
Electron Crystallography ◽  
Peltier Element ◽  
Protein Ratio ◽  
Precise Control ◽  
3 Dimensional

Reconstitution of solubilized and purified membrane proteins in the presence of phospholipids into vesicles allows their functions to be studied by simple bulk measurements (e.g. diffusion of differently sized solutes) or by conductance measurements after transformation into planar membranes. On the other hand, reconstitution into regular protein-lipid arrays, usually forming at a specific lipid-to-protein ratio, provides the basis for determining the 3-dimensional structure of membrane proteins employing the tools of electron crystallography.To refine reconstitution conditions for reproducibly inducing formation of large and highly ordered protein-lipid membranes that are suitable for both electron crystallography and patch clamping experiments aimed at their functional characterization, we built a flow-dialysis device that allows precise control of temperature and flow-rate (Fig. 1). The flow rate is generated by a peristaltic pump and can be adjusted from 1 to 500 ml/h. The dialysis buffer is brought to a preselected temperature during its travel through a meandering path before it enters the dialysis reservoir. A Z-80 based computer controls a Peltier element allowing the temperature profile to be programmed as function of time.

scholarly journals Membrane protein engineering to the rescue

2018 ◽  
Vol 46 (6) ◽  
pp. 1541-1549
Author(s):  
Andrea E. Rawlings
Keyword(s):  
Membrane Proteins ◽  
Membrane Protein ◽  
Protein Engineering ◽  
Mutation Screening ◽  
Water Soluble ◽  
Scaffold Proteins ◽  
Major Barrier ◽  
Expression Levels ◽  
Aqueous Environments ◽  
Protein Research

The inherent hydrophobicity of membrane proteins is a major barrier to membrane protein research and understanding. Their low stability and solubility in aqueous environments coupled with poor expression levels make them a challenging area of research. For many years, the only way of working with membrane proteins was to optimise the environment to suit the protein, through the use of different detergents, solubilising additives, and other adaptations. However, with innovative protein engineering methodologies, the membrane proteins themselves are now being adapted to suit the environment. This mini-review looks at the types of adaptations which are applied to membrane proteins from a variety of different fields, including water solubilising fusion tags, thermostabilising mutation screening, scaffold proteins, stabilising protein chimeras, and isolating water-soluble domains.

Bacterial small membrane proteins: the Swiss army knife of regulators at the lipid bilayer

2021 ◽  
Author(s):  
Srujana S. Yadavalli ◽  
Jing Yuan
Keyword(s):  
Membrane Proteins ◽  
Drug Targets ◽  
Open Reading Frames ◽  
E Coli ◽  
Cellular Processes ◽  
Small Proteins ◽  
Alternative Drug ◽  
Genome Annotations ◽  
Partner Proteins ◽  
Small Open Reading Frames

Small membrane proteins represent a subset of recently discovered small proteins (≤100 amino acids), which are a ubiquitous class of emerging regulators underlying bacterial adaptation to environmental stressors. Until relatively recently, small open reading frames encoding these proteins were not designated as genes in genome annotations. Therefore, our understanding of small protein biology was primarily limited to a few candidates associated with previously characterized larger partner proteins. Following the first systematic analyses of small proteins in E. coli over a decade ago, numerous small proteins have been uncovered across different bacteria. An estimated one-third of these newly discovered proteins are localized to the cell membrane, where they may interact with distinct groups of membrane proteins such as signal receptors, transporters, and enzymes, and affect their activities. Recently, there has been considerable progress in functionally characterizing small membrane protein regulators aided by innovative tools adapted specifically to study small proteins. Our review covers prototypical proteins that modulate a broad range of cellular processes such as transport, signal transduction, stress response, respiration, cell division, sporulation as well as membrane stability. Thus, small membrane proteins represent a versatile group of regulators of physiology not just at the membrane but the whole cell. Additionally, small membrane proteins have the potential for clinical applications, where some of the proteins may act as antibacterial agents themselves, while others serve as alternative drug targets for the development of novel antimicrobials.

scholarly journals Fluorescence Approaches for Characterizing Ion Channels in Synthetic Bilayers

Membranes ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 857
Author(s):  
Md. Sirajul Islam ◽  
James P. Gaston ◽  
Matthew A. B. Baker
Keyword(s):  
Ion Channels ◽  
Membrane Proteins ◽  
Lipid Bilayers ◽  
Lipid Membranes ◽  
Protein Composition ◽  
Cellular Processes ◽  
Model Lipid Membranes ◽  
Wide Range ◽  
Lipid Environment

Ion channels are membrane proteins that play important roles in a wide range of fundamental cellular processes. Studying membrane proteins at a molecular level becomes challenging in complex cellular environments. Instead, many studies focus on the isolation and reconstitution of the membrane proteins into model lipid membranes. Such simpler, in vitro, systems offer the advantage of control over the membrane and protein composition and the lipid environment. Rhodopsin and rhodopsin-like ion channels are widely studied due to their light-interacting properties and are a natural candidate for investigation with fluorescence methods. Here we review techniques for synthesizing liposomes and for reconstituting membrane proteins into lipid bilayers. We then summarize fluorescence assays which can be used to verify the functionality of reconstituted membrane proteins in synthetic liposomes.

scholarly journals Intrinsically Disordered Proteins as Regulators of Transient Biological Processes and as Untapped Drug Targets

Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2118
Author(s):  
Yusuke Hosoya ◽  
Junko Ohkanda
Keyword(s):  
Drug Targets ◽  
Intrinsically Disordered Proteins ◽  
Dynamic Control ◽  
Disordered Proteins ◽  
Biological Processes ◽  
Phase Separations ◽  
Cellular Processes ◽  
Intrinsically Disordered ◽  
New Drug ◽  
Liquid Phase Separations

Intrinsically disordered proteins (IDPs) are critical players in the dynamic control of diverse cellular processes, and provide potential new drug targets because their dysregulation is closely related to many diseases. This review focuses on several medicinal studies that have identified low-molecular-weight inhibitors of IDPs. In addition, clinically relevant liquid–liquid phase separations—which critically involve both intermolecular interactions between IDPs and their posttranslational modification—are analyzed to understand the potential of IDPs as new drug targets.

Evolutionary Consequences of Tradeoffs between Yield and Rate of ATP Production

2002 ◽  
Vol 216 (1) ◽  
Author(s):  
Thomas Pfeiffer ◽  
Sebastian Bonhoeffer
Keyword(s):  
Game Theory ◽  
Population Dynamics ◽  
Energy Metabolism ◽  
Adenosine Triphosphate ◽  
Organic Material ◽  
High Yield ◽  
Atp Production ◽  
Cellular Processes ◽  
Quantitative Properties ◽  
Evolutionary Consequences

Adenosine triphosphate (ATP) is a key compound in the energy metabolism of cells and is required to drive vital biochemical reactions. In heterotrophic organisms ATP production is coupled to the degradation of energy-rich organic material taken up from the environment. In the transfer of the environmental energy to cellular processes heterotrophs face a tradeoff, since the conversion of the environmental energy into ATP cannot be both maximally fast and efficient. Here we show how tradeoffs between rate and yield of ATP production arise firstly from thermodynamical principles, and secondly for the ATP production by respiration and fermentation. Using methods derived from game theory and population dynamics we investigate the evolutionary consequences for both tradeoffs. We show that spatially structured environments enable the evolution of efficient pathways with high yield. The strategies of ATP production realized in a population, however, depend on the quantitative properties of the tradeoffs.

Block poly(Ala)-poly(Lys). A water-soluble model for intrinsic membrane proteins?

1979 ◽  
Vol 557 (2) ◽  
pp. 331-339 ◽  
Author(s):  
L. Vitello ◽  
G.C. Kresheck ◽  
R.J. Albers ◽  
J.E. Erman ◽  
G. Vanderkooi
Keyword(s):  
Membrane Proteins ◽  
Water Soluble ◽  
Soluble Model

scholarly journals High-yield Aromatic Monomers and Pure Cellulose Production by Oxidative Catalytic Fractionation of Lignocellulose in the presence of CuO Nanoparticles

2021 ◽  
Author(s):  
Yuting Zhu ◽  
Yuhe Liao ◽  
Luying Lu ◽  
Wei Lv ◽  
Jing Liu ◽  
...  
Keyword(s):  
Cuo Nanoparticles ◽  
Water Soluble ◽  
High Yield ◽  
Cellulose Production ◽  
Carbon Efficiency ◽  
Mild Conditions ◽  
Pure Cellulose ◽  
Cuo Nps ◽  
Lignocellulosic Feedstock ◽  
High Cellulose

<a></a><a>Herein, we report the catalytic use of multifunctional CuO nanoparticles (NPs) to oxidatively fractionate lignocellulosic feedstock with dioxygen in aqueous NaOH under mild conditions . In presence of CuO NPs, lignocellulose is fractionated into three parts, overall yielding 90% carbon efficiency. Lignin is converted to up to 45.6 wt% in organic soluble aromatic aldehyde monomers, rich in vanillin and syringaldehyde, the value surpassing the theoretical one based on b-O-4 bond content, indicating significant cleavage of other ether bonds. All hemicellulose is selectively converted into water soluble small (di)acids, mainly to oxalic acid. Up to 81% of cellulose, in contrast, is obtained as a white crystalline residue with high cellulose purity (over 95%), which can readily be transformed into high quality nanocellulose, useful in many applications.</a>

scholarly journals Membrane Proteins Are Dramatically Less Conserved than Water-Soluble Proteins across the Tree of Life

2016 ◽  
Vol 33 (11) ◽  
pp. 2874-2884 ◽  
Author(s):  
Victor Sojo ◽  
Christophe Dessimoz ◽  
Andrew Pomiankowski ◽  
Nick Lane
Keyword(s):  
Membrane Proteins ◽  
Soluble Proteins ◽  
Tree Of Life ◽  
Water Soluble
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