-
Biochemical Society Transactions Feb 2017The application of membrane proteins in biotechnology requires robust, durable reconstitution systems that enhance their stability and support their functionality in a... (Review)
Review
The application of membrane proteins in biotechnology requires robust, durable reconstitution systems that enhance their stability and support their functionality in a range of working environments. Vesicular architectures are highly desirable to provide the compartmentalisation to utilise the functional transmembrane transport and signalling properties of membrane proteins. Proteoliposomes provide a native-like membrane environment to support membrane protein function, but can lack the required chemical and physical stability. Amphiphilic block copolymers can also self-assemble into polymersomes: tough vesicles with improved stability compared with liposomes. This review discusses the reconstitution of membrane proteins into polymersomes and the more recent development of hybrid vesicles, which blend the robust nature of block copolymers with the biofunctionality of lipids. These novel synthetic vesicles hold great promise for enabling membrane proteins within biotechnologies by supporting their enhanced performance and could also contribute to fundamental biochemical and biophysical research by improving the stability of membrane proteins that are challenging to work with.
Topics: Biological Transport; Biotechnology; Lipid Bilayers; Membrane Lipids; Membrane Proteins; Models, Chemical; Models, Molecular; Polymers; Proteolipids; Unilamellar Liposomes
PubMed: 28202656
DOI: 10.1042/BST20160019 -
American Journal of Physiology. Cell... Feb 2022Duchenne muscular dystrophy (DMD) is an inherited muscle wasting disease. Metabolic impairments and oxidative stress are major secondary mechanisms that severely worsen...
Duchenne muscular dystrophy (DMD) is an inherited muscle wasting disease. Metabolic impairments and oxidative stress are major secondary mechanisms that severely worsen muscle function in DMD. Here, we sought to determine whether germline reduction or ablation of sarcolipin (SLN), an inhibitor of sarco/endoplasmic reticulum (SR) Ca ATPase (SERCA), improves muscle metabolism and ameliorates muscle pathology in the mouse model of DMD. Glucose and insulin tolerance tests show that glucose clearance rate and insulin sensitivity were improved in the SLN haploinsufficient () and SLN-deficient () mice. The histopathological analysis shows that fibrosis and necrosis were significantly reduced in muscles of and mice. SR Ca uptake, mitochondrial complex protein levels, complex activities, mitochondrial Ca uptake and release, and mitochondrial metabolism were significantly improved, and lipid peroxidation and protein carbonylation were reduced in the muscles of and mice. These data demonstrate that reduction or ablation of SLN expression can improve muscle metabolism, reduce oxidative stress, decrease muscle pathology, and protects the mice from glucose intolerance.
Topics: Animals; Blood Glucose; Female; Male; Mice; Mice, Inbred C57BL; Mice, Inbred mdx; Mice, Knockout; Muscle Proteins; Muscle, Skeletal; Oxidative Stress; Proteolipids
PubMed: 34986021
DOI: 10.1152/ajpcell.00125.2021 -
European Journal of Pharmaceutical... Feb 2017Extracellular vesicles (EVs) mediate normal physiological homeostasis and pathological processes by facilitating intercellular communication. Research of EVs in basic...
Extracellular vesicles (EVs) mediate normal physiological homeostasis and pathological processes by facilitating intercellular communication. Research of EVs in basic science and clinical settings requires both methodological standardization and development of reference materials (RM). Here, we show insights and results of biological RM development for EV studies. We used a three-step approach to find and develop a biological RM. First, a literature search was done to find candidates for biological RMs. Second, a questionnaire was sent to EV researchers querying the preferences for RM and their use. Third, a biological RM was selected, developed, characterized, and evaluated. The responses to the survey demonstrated a clear and recognized need for RM optimized for the calibration of EV measurements. Based on the literature, naturally occurring and produced biological RM, such as virus particles and liposomes, were proposed as RM. However, none of these candidate RMs have properties completely matching those of EVs, such as size and refractive index distribution. Therefore, we evaluated the use of nanoerythrosomes (NanoE), vesicles produced from erythrocytes, as a potential biological RM. The strength of NanoE is their resemblance to EVs. Compared to the erythrocyte-derived EVs (eryEVs), NanoE have similar morphology, a similar refractive index (1.37), larger diameter (70% of the NanoE are over 200nm), and increased positive staining for CD235a and lipids (Di-8-ANEPPS) (58% and 67% in NanoE vs. 21% and 45% in eryEVs, respectively). Altogether, our results highlight the general need to develop and validate new RM with similar physical and biochemical properties as EVs to standardize EV measurements between instruments and laboratories.
Topics: Erythrocytes; Extracellular Vesicles; Flow Cytometry; Humans; Microscopy, Electron, Transmission; Nanostructures; Proteolipids; Reference Standards
PubMed: 27622921
DOI: 10.1016/j.ejps.2016.09.008 -
Biochimica Et Biophysica Acta Jan 2015The motional averaging of powder pattern line shapes is one of the most fundamental aspects of sold-state NMR. Since membrane proteins in liquid crystalline phospholipid... (Review)
Review
The motional averaging of powder pattern line shapes is one of the most fundamental aspects of sold-state NMR. Since membrane proteins in liquid crystalline phospholipid bilayers undergo fast rotational diffusion, all of the signals reflect the angles of the principal axes of their dipole-dipole and chemical shift tensors with respect to the axis defined by the bilayer normal. The frequency span and sign of the axially symmetric powder patterns that result from motional averaging about a common axis provide sufficient structural restraints for the calculation of the three-dimensional structure of a membrane protein in a phospholipid bilayer environment. The method is referred to as rotationally aligned (RA) solid-state NMR and demonstrated with results on full-length, unmodified membrane proteins with one, two, and seven trans-membrane helices. RA solid-state NMR is complementary to other solid-state NMR methods, in particular oriented sample (OS) solid-state NMR of stationary, aligned samples. Structural distortions of membrane proteins from the truncations of terminal residues and other sequence modifications, and the use of detergent micelles instead of phospholipid bilayers have also been demonstrated. Thus, it is highly advantageous to determine the structures of unmodified membrane proteins in liquid crystalline phospholipid bilayers under physiological conditions. RA solid-state NMR provides a general method for obtaining accurate and precise structures of membrane proteins under near-native conditions.
Topics: Amino Acid Sequence; Diffusion; Magnetic Resonance Spectroscopy; Membrane Proteins; Molecular Sequence Data; Protein Folding; Proteolipids; Rotation
PubMed: 24747039
DOI: 10.1016/j.bbamem.2014.04.002 -
Biochimica Et Biophysica Acta.... Apr 2024The proteolipid code determines how cytosolic proteins find and remodel membrane surfaces. Here, we investigate how this process works with sorting nexins Snx1 and Snx3.... (Review)
Review
The proteolipid code determines how cytosolic proteins find and remodel membrane surfaces. Here, we investigate how this process works with sorting nexins Snx1 and Snx3. Both proteins form sorting machines by recognizing membrane zones enriched in phosphatidylinositol 3-phosphate (PI3P), phosphatidylserine (PS) and cholesterol. This co-localized combination forms a unique "lipid codon" or lipidon that we propose is responsible for endosomal targeting, as revealed by structures and interactions of their PX domain-based readers. We outline a membrane recognition and remodeling mechanism for Snx1 and Snx3 involving this code element alongside transmembrane pH gradients, dipole moment-guided docking and specific protein-protein interactions. This generates an initial membrane-protein assembly (memtein) that then recruits retromer and additional PX proteins to recruit cell surface receptors for sorting to the trans-Golgi network (TGN), lysosome and plasma membranes. Post-translational modification (PTM) networks appear to regulate how the sorting machines form and operate at each level. The commonalities and differences between these sorting nexins show how the proteolipid code orchestrates parallel flows of molecular information from ribosome emergence to organelle genesis, and illuminates a universally applicable model of the membrane.
Topics: Carrier Proteins; Vesicular Transport Proteins; Sorting Nexins; Protein Transport; Proteolipids
PubMed: 38408696
DOI: 10.1016/j.bbamem.2024.184305 -
Clinical Biochemistry Apr 1991Multiple sclerosis (MS) and a number of related distinctive diseases are characterized by the active degradation of central nervous system (CNS) myelin, an axonal sheath... (Review)
Review
Multiple sclerosis (MS) and a number of related distinctive diseases are characterized by the active degradation of central nervous system (CNS) myelin, an axonal sheath comprised essentially of proteins and lipids. These demyelinating diseases appear to arise from complex interactions of genetic, immunological, infective, and biochemical mechanisms. While circumstances of MS etiology remain hypothetical, one persistent theme involves recognition by the immune system of myelin-specific antigens derived from myelin basic protein (MBP), the most abundant extrinsic myelin membrane protein, and/or another equally susceptible myelin protein or lipid component. Knowledge of the biochemical and physical-chemical properties of myelin proteins and lipids, particularly their composition, organization, structure, and accessibility with respect to the compacted myelin multilayers, thus becomes central to the understanding of how and why these antigens become selected during the development of MS. This review focuses on current understanding of the molecular basis underlying demyelinating disease as it may relate to the impact of the various protein and lipid components on myelin morphology; the precise molecular architecture of this membrane as dictated by protein-lipid and lipid-lipid interactions; and the relationship, if any, between the protein/lipid components and the destruction of myelin in pathological situations.
Topics: Amino Acid Sequence; Animals; Central Nervous System; Demyelinating Diseases; Humans; Lipid Metabolism; Lipids; Molecular Sequence Data; Myelin Basic Protein; Myelin Proteins; Myelin Sheath; Proteolipids; Uteroglobin
PubMed: 1710177
DOI: 10.1016/0009-9120(91)90421-a -
FEBS Letters Nov 2018Neurotransmitter release occurs in the form of quantal events by fusion of secretory vesicles with the plasma membrane, and begins with the formation of a fusion pore... (Review)
Review
Neurotransmitter release occurs in the form of quantal events by fusion of secretory vesicles with the plasma membrane, and begins with the formation of a fusion pore that has a conductance similar to that of a large ion channel or gap junction. In this review, we propose mechanisms of fusion pore formation and discuss their implications for fusion pore structure and function. Accumulating evidence indicates a direct role of soluble N-ethylmaleimide-sensitive-factor attachment receptor proteins in the opening of fusion pores. Fusion pores are likely neither protein channels nor purely lipid, but are of proteolipidic composition. Future perspectives to gain better insight into the molecular structure of fusion pores are discussed.
Topics: Animals; Cell Membrane; Exocytosis; Humans; Membrane Fusion; Proteolipids; SNARE Proteins; Secretory Vesicles
PubMed: 29904915
DOI: 10.1002/1873-3468.13160 -
International Journal of Molecular... Aug 2021The sarco-endoplasmic reticulum calcium ATPase (SERCA) is responsible for maintaining calcium homeostasis in all eukaryotic cells by actively transporting calcium from... (Review)
Review
The sarco-endoplasmic reticulum calcium ATPase (SERCA) is responsible for maintaining calcium homeostasis in all eukaryotic cells by actively transporting calcium from the cytosol into the sarco-endoplasmic reticulum (SR/ER) lumen. Calcium is an important signaling ion, and the activity of SERCA is critical for a variety of cellular processes such as muscle contraction, neuronal activity, and energy metabolism. SERCA is regulated by several small transmembrane peptide subunits that are collectively known as the "regulins". Phospholamban (PLN) and sarcolipin (SLN) are the original and most extensively studied members of the regulin family. PLN and SLN inhibit the calcium transport properties of SERCA and they are required for the proper functioning of cardiac and skeletal muscles, respectively. Myoregulin (MLN), dwarf open reading frame (DWORF), endoregulin (ELN), and another-regulin (ALN) are newly discovered tissue-specific regulators of SERCA. Herein, we compare the functional properties of the regulin family of SERCA transmembrane peptide subunits and consider their regulatory mechanisms in the context of the physiological and pathophysiological roles of these peptides. We present new functional data for human MLN, ELN, and ALN, demonstrating that they are inhibitors of SERCA with distinct functional consequences. Molecular modeling and molecular dynamics simulations of SERCA in complex with the transmembrane domains of MLN and ALN provide insights into how differential binding to the so-called inhibitory groove of SERCA-formed by transmembrane helices M2, M6, and M9-can result in distinct functional outcomes.
Topics: Animals; Calcium; Calcium-Binding Proteins; Humans; Models, Molecular; Muscle Proteins; Proteolipids; Sarcoplasmic Reticulum Calcium-Transporting ATPases
PubMed: 34445594
DOI: 10.3390/ijms22168891 -
Journal of Molecular and Cellular... May 2007The cardiac sarcoplasmic reticulum calcium ATPase (SERCA2a) plays a critical role in maintaining the intracellular calcium homeostasis during cardiac contraction and... (Review)
Review
The cardiac sarcoplasmic reticulum calcium ATPase (SERCA2a) plays a critical role in maintaining the intracellular calcium homeostasis during cardiac contraction and relaxation. It has been well documented over the years that altered expression and activity of SERCA2a can lead to systolic and diastolic dysfunction. The activity of SERCA2a is regulated by two structurally similar proteins, phospholamban (PLB) and sarcolipin (SLN). Although, the relevance of PLB has been extensively studied over the years, the role SLN in cardiac physiology is an emerging field of study. This review focuses on the advances in the understanding of the regulation of SERCA2a by SLN and PLB. In particular, it highlights the similarities and differences between the two proteins and their roles in cardiac patho-physiology.
Topics: Animals; Calcium-Binding Proteins; Heart; Humans; Muscle Proteins; Myocardium; Proteolipids; Sarcoplasmic Reticulum Calcium-Transporting ATPases
PubMed: 17442337
DOI: 10.1016/j.yjmcc.2007.03.738 -
Biochimica Et Biophysica Acta Nov 1998Pulmonary surfactant contains less than 1 wt% of the very non-polar surfactant protein C (SP-C). In most animal species the major form of SP-C is a 35-residue peptide... (Review)
Review
Pulmonary surfactant contains less than 1 wt% of the very non-polar surfactant protein C (SP-C). In most animal species the major form of SP-C is a 35-residue peptide chain which contains two thioester-linked palmitoyl groups, giving a total molecular mass of 4.2 kDa. Several minor variants of SP-C exist, formed from N-terminal truncation, lysine palmitoylation, methionine oxidation and C-terminal esterification. The primary structure is evolutionarily conserved and SP-C appears to be the only constituent which is unique to pulmonary surfactant, indicating important and specific functions. The three-dimensional structure in an aqueous mixed organic solvent determined by NMR spectroscopy revealed one continuous 37 A long alpha-helix encompassing residues 9-34 as the only regular structural element. The central 23 A of the helix contains exclusively aliphatic residues with branched side-chains, mainly valines, and exposes an all-hydrophobic regular surface. The size of the entire helix perfectly matches the thickness of a fluid dipalmitoylphosphatidylcholine membrane, and the all-hydrophobic part of the helix matches the acyl-chain part of such a bilayer. This supports a transmembrane orientation of SP-C in pulmonary surfactant bilayers. In a phospholipid monolayer, the SP-C helix is tilted, thereby maximizing the interactions with the lipid acyl-chains also in this environment. The palmitoylcysteines of SP-C, which are located in the flexibly disordered N-terminal octapeptide segment, appear to be important both for integrity of the alpha-helical structure and for functional properties. Since the conformation of the N-terminal part in a phospholipid environment is not known, the mechanisms whereby the SP-C thioester-linked palmitoyl chains affect structure and function remain to be determined.
Topics: Amino Acid Sequence; Molecular Sequence Data; Phospholipids; Protein Conformation; Protein Isoforms; Proteolipids; Pulmonary Surfactants; Structure-Activity Relationship
PubMed: 9813304
DOI: 10.1016/s0925-4439(98)00065-9