Establishing the role of PLVAP in protein-losing enteropathy: a homozygous missense variant leads to an attenuated phenotype

2018 ◽  
Vol 55 (11) ◽  
pp. 779-784 ◽  
Author(s):  
Alina Kurolap ◽  
Orly Eshach-Adiv ◽  
Claudia Gonzaga-Jauregui ◽  
Katya Dolnikov ◽  
Adi Mory ◽  
...  
Keyword(s):  
Barrier Function ◽  
Protein Function ◽  
Transmembrane Domain ◽  
Autosomal Recessive Inheritance ◽  
Missense Variant ◽  
Protein Loss ◽  
Protein Losing Enteropathy ◽  
Family Based ◽  
And Function

BackgroundIntestinal integrity is essential for proper nutrient absorption and tissue homeostasis, with damage leading to enteric protein loss, that is, protein-losing enteropathy (PLE). Recently, homozygous nonsense variants in the plasmalemma vesicle-associated protein gene (PLVAP) were reported in two patients with severe congenital PLE. PLVAP is the building block of endothelial cell (EC) fenestral diaphragms; its importance in barrier function is supported by mouse models of Plvap deficiency.ObjectiveTo genetically diagnose two first-degree cousins once removed, who presented with PLE at ages 22 and 2.5 years.MethodsFamily-based whole exome sequencing was performed based on an autosomal recessive inheritance model. In silico analyses were used to predict variant impact on protein structure and function.ResultsWe identified a rare homozygous variant (NM_031310.2:c.101T>C;p.Leu34Pro) in PLVAP, which co-segregated with the disease. Leu34 is predicted to be located in a highly conserved, hydrophobic, α-helical region within the protein’s transmembrane domain, suggesting Leu34Pro is likely to disrupt protein function and/or structure. Electron microscopy and PLVAP immunohistochemistry demonstrated apparently normal diaphragm morphology, predicted to be functionally affected.ConclusionsBiallelic missense variants in PLVAP can cause an attenuated form of the PLE and hypertriglyceridaemia syndrome. Our findings support the role of PLVAP in the pathophysiology of PLE, expand the phenotypic and mutation spectrums and underscore PLVAP’s importance in EC barrier function in the gut.

scholarly journals The Nlrp6 inflammasome is not required for baseline colonic inner mucus layer formation or function

2019 ◽  
Vol 216 (11) ◽  
pp. 2602-2618 ◽  
Author(s):  
Joana K. Volk ◽  
Elisabeth E.L. Nyström ◽  
Sjoerd van der Post ◽  
Beatriz M. Abad ◽  
Bjoern O. Schroeder ◽  
...  
Keyword(s):  
Barrier Function ◽  
Independent Effect ◽  
Mucus Layer ◽  
Effect Analysis ◽  
Innate Immune Signaling ◽  
Inflammatory Bowel ◽  
And Function ◽  
Deficient Mice ◽  
Inflammasome Activity

The inner mucus layer (IML) is a critical barrier that protects the colonic epithelium from luminal threats and inflammatory bowel disease. Innate immune signaling is thought to regulate IML formation via goblet cell Nlrp6 inflammasome activity that controls secretion of the mucus structural component Muc2. We report that isolated colonic goblet cells express components of several inflammasomes; however, analysis of IML properties in multiple inflammasome-deficient mice, including littermate-controlled Nlrp6−/−, detect a functional IML barrier in all strains. Analysis of mice lacking inflammasome substrate cytokines identifies a defective IML in Il18−/− mice, but this phenotype is ultimately traced to a microbiota-driven, Il18-independent effect. Analysis of phenotypic transfer between IML-deficient and IML-intact mice finds that the Bacteroidales family S24-7 (Muribaculaceae) and genus Adlercrutzia consistently positively covary with IML barrier function. Together, our results demonstrate that baseline IML formation and function is independent of inflammasome activity and highlights the role of the microbiota in determining IML barrier function.

scholarly journals Beyond Anchoring: the Expanding Role of the Hendra Virus Fusion Protein Transmembrane Domain in Protein Folding, Stability, and Function

2012 ◽  
Vol 86 (6) ◽  
pp. 3003-3013 ◽  
Author(s):  
E. C. Smith ◽  
M. R. Culler ◽  
L. M. Hellman ◽  
M. G. Fried ◽  
T. P. Creamer ◽  
...  
Keyword(s):  
Protein Folding ◽  
Fusion Protein ◽  
Transmembrane Domain ◽  
Hendra Virus ◽  
Virus Fusion ◽  
And Function

scholarly journals Role of the N-terminal transmembrane domain in the endo-lysosomal targeting and function of the human ABCB6 protein

2015 ◽  
Vol 467 (1) ◽  
pp. 127-139 ◽  
Author(s):  
Katalin Kiss ◽  
Nora Kucsma ◽  
Anna Brozik ◽  
Gabor E. Tusnady ◽  
Ptissam Bergam ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Transmembrane Domain ◽  
Intracellular Localization ◽  
Atp Binding ◽  
Multivesicular Bodies ◽  
Molecular Dissection ◽  
Terminal Domain ◽  
Lysosomal Targeting ◽  
And Function

The intracellular localization of ATP-binding cassette, sub family B (ABCB) 6 is a matter of debate. We show that ABCB6 is internalized from the plasma membrane to multivesicular bodies and lysosomes. Molecular dissection of the ABCB6 protein reveals a role of its N-terminal domain in targeting.

scholarly journals Trynity controls epidermal barrier function and respiratory tube maturation in Drosophila by modulating apical extracellular matrix nano-patterning

2018 ◽  
Author(s):  
Yuki Itakura ◽  
Sachi Inagaki ◽  
Housei Wada ◽  
Shigeo Hayashi
Keyword(s):  
Extracellular Matrix ◽  
Barrier Function ◽  
Essential Gene ◽  
Epidermal Barrier ◽  
Summary Statement ◽  
Domain Protein ◽  
And Function ◽  
Envelope Layer ◽  
Nano Patterning

AbstractThe outer surface of insects is covered by the cuticle, which is derived from the apical extracellular matrix (aECM). The aECM is secreted by epidermal cells during embryogenesis. The aECM exhibits large variations in structure, function, and constituent molecules, reflecting the enormous diversity in insect appearances. To investigate the molecular principles of aECM organization and function, here we studied the role of a conserved aECM protein, the ZP domain protein Trynity, in Drosophila melanogaster. We first identified trynity as an essential gene for epidermal barrier function. trynity mutation caused disintegration of the outermost envelope layer of the cuticle, resulting in small- molecule leakage and in growth and molting defects. In addition, the tracheal tubules of trynity mutants showed defects in pore-like structures of the cuticle, and the mutant tracheal cells failed to absorb luminal proteins and liquid. Our findings indicated that trynity plays essential roles in organizing nano-level structures in the envelope layer of the cuticle that both restrict molecular trafficking through the epidermis and promote the massive absorption pulse in the trachea.Summary StatementThe zona pellucida domain protein Trynity controls the structural organization and function of the apical extracellular matrix in the epidermis and trachea of Drosophila.

scholarly journals The Structure of the Membrane Protein of SARS-CoV-2 Resembles the Sugar Transporter semiSWEET

2020 ◽  
Author(s):  
Sunil Thomas
Keyword(s):  
In Silico ◽  
Transmembrane Domain ◽  
Sugar Transport ◽  
Protein S ◽  
M Protein ◽  
Sugar Transporter ◽  
Structural Protein ◽  
And Function ◽  
In Silico Analyses

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is responsible for the disease COVID-19 that has decimated the health and economy of our planet. The virus causes the disease not only in people but also in companion and wild animals. People with diabetes are at risk of the disease. As yet we do not know why the virus is highly successful in causing the pandemic within 3 months of its first report. The structural proteins of SARS include, membrane glycoprotein (M), envelope protein (E), nucleocapsid protein (N) and the spike protein (S). The structure and function of the most abundant structural protein of SARS-CoV-2, the membrane (M) glycoprotein is not fully understood. Using in silico analyses we determined the structure and potential function of the M protein. In silico analyses showed that the M protein of SARS-CoV-2 has a triple helix bundle, form a single 3-transmembrane domain (TM), and are homologous to the prokaryotic sugar transport protein semiSWEET. The advantage and role of sugar transporter like structures in viruses are unknown. If they are involved in energy metabolism, they may aid in the rapid proliferation and replication of the virus. Biological experiments should be performed to validate the presence and function of the semiSWEET sugar transporter.

scholarly journals The Conserved Positive Charge in the Transmembrane Domain of HIV Gp41 Contributes to Its Intrinsic Preference for Trimerization

2019 ◽  
Author(s):  
Timothy Reichart ◽  
Daniel Leaman ◽  
Daniel Sands ◽  
Michael Zwick ◽  
Philip Dawson
Keyword(s):  
Hiv Infection ◽  
Positive Charge ◽  
Transmembrane Domain ◽  
Structure And Function ◽  
Model Membranes ◽  
Viral Membrane ◽  
Glycoprotein Gp41 ◽  
Tm Domain ◽  
And Function

The transmembrane (TM) domain of HIV glycoprotein gp41 anchors the envelope (Env) spike in the viral membrane and is highly conserved. The mid-span arginine 696 is particularly conserved, and the only other residue found in this position is lysine. Seeking to examine the role of this conserved positive charge in the structure and function of the gp41 TM domain, we synthesized a series of peptides corresponding to this region. Analysis of the peptides in a previously validated fluorescence assay in model membranes showed that the native TM domain is trimeric. Peptides in which the intramembrane arginine was mutated to alanine showed significantly lower trimerization propensity. In contrast, this mutation in the context of infectious pseudovirus caused only modest decreases in viral stability and infectivity. We propose a model to explain the importance of this charge to gp41 structure and to HIV infection.

PROTEIN DYNAMICS IN PHOSPHORYLATION-MEDIATED ALLOSTERY PROBED BY AMIDE EXCHANGE MASS SPECTROMETRY

COSMOS ◽  
2013 ◽  
Vol 09 (01) ◽  
pp. 19-27
Author(s):  
MADHUBRATA GHOSH ◽  
GANESH S. ANAND
Keyword(s):  
Mass Spectrometry ◽  
Protein Dynamics ◽  
Protein Function ◽  
Post Translational Modifications ◽  
Exchange Mass Spectrometry ◽  
Amide Exchange ◽  
Hydrogen Deuterium ◽  
Deuterium Exchange Mass Spectrometry ◽  
And Function

A major goal of molecular biology is to correlate molecular structure with function. Since most enzymes and biological catalysts are proteins, the focus for correlating 'form' with 'function' has been entirely on protein macromolecular structure. It is obvious that any understanding of protein function must come through an understanding protein dynamics. Furthermore, all of the regulatory reactions are through changes in dynamics brought about by post-translational modifications, the most important of which is phosphorylation. This review highlights the important role of covalent phosphorylation and noncovalent phosphates in regulating allosteric effects and function through a study of protein dynamics. Mass spectrometry is a relatively new and increasingly important tool for describing protein dynamics. All examples described in this review have been studied by amide hydrogen/deuterium exchange mass spectrometry.

scholarly journals The Conserved Positive Charge in the Transmembrane Domain of HIV Gp41 Contributes to Its Intrinsic Preference for Trimerization

2020 ◽  
Author(s):  
Timothy Reichart ◽  
Daniel Leaman ◽  
Daniel Sands ◽  
Michael Zwick ◽  
Philip Dawson
Keyword(s):  
Hiv Infection ◽  
Positive Charge ◽  
Transmembrane Domain ◽  
Structure And Function ◽  
Model Membranes ◽  
Viral Membrane ◽  
Glycoprotein Gp41 ◽  
Tm Domain ◽  
And Function

The transmembrane (TM) domain of HIV glycoprotein gp41 anchors the envelope (Env) spike in the viral membrane and is highly conserved. The mid-span arginine 696 is particularly conserved, and the only other residue found in this position is lysine. Seeking to examine the role of this conserved positive charge in the structure and function of the gp41 TM domain, we synthesized a series of peptides corresponding to this region. Analysis of the peptides in a previously validated fluorescence assay in model membranes showed that the native TM domain is trimeric. Peptides in which the intramembrane arginine was mutated to alanine showed significantly lower trimerization propensity. In contrast, this mutation in the context of infectious pseudovirus caused only modest decreases in viral stability and infectivity. We propose a model to explain the importance of this charge to gp41 structure and to HIV infection.

scholarly journals Structural and Functional Importance of Transmembrane Domain 3 (TM3) in the Aspartate:Alanine Antiporter AspT: Topology and Function of the Residues of TM3 and Oligomerization of AspT

2009 ◽  
Vol 191 (7) ◽  
pp. 2122-2132 ◽  
Author(s):  
Kei Nanatani ◽  
Peter C. Maloney ◽  
Keietsu Abe
Keyword(s):  
Transmembrane Domain ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Hydrophobic Core ◽  
Amino Acid Residues ◽  
Cysteine Scanning Mutagenesis ◽  
Domain 3 ◽  
Hydrophilic Residues ◽  
And Function

ABSTRACT AspT, the aspartate:alanine antiporter of Tetragenococcus halophilus, a membrane protein of 543 amino acids with 10 putative transmembrane (TM) helices, is the prototype of the aspartate:alanine exchanger (AAE) family of transporters. Because TM3 (isoleucine 64 to methionine 85) has many amino acid residues that are conserved among members of the AAE family and because TM3 contains two charged residues and four polar residues, it is thought to be located near (or to form part of) the substrate translocation pathway that includes the binding site for the substrates. To elucidate the role of TM3 in the transport process, we carried out cysteine-scanning mutagenesis. The substitutions of tyrosine 75 and serine 84 had the strongest inhibitory effects on transport (initial rates of l-aspartate transport were below 15% of the rate for cysteine-less AspT). Considerable but less-marked effects were observed upon the replacement of methionine 70, phenylalanine 71, glycine 74, arginine 76, serine 83, and methionine 85 (initial rates between 15% and 30% of the rate for cysteine-less AspT). Introduced cysteine residues at the cytoplasmic half of TM3 could be labeled with Oregon green maleimide (OGM), whereas cysteines close to the periplasmic half (residues 64 to 75) were not labeled. These results suggest that TM3 has a hydrophobic core on the periplasmic half and that hydrophilic residues on the cytoplasmic half of TM3 participate in the formation of an aqueous cavity in membranes. Furthermore, the presence of l-aspartate protected the cysteine introduced at glycine 62 against a reaction with OGM. In contrast, l-aspartate stimulated the reactivity of the cysteine introduced at proline 79 with OGM. These results demonstrate that TM3 undergoes l-aspartate-induced conformational alterations. In addition, nonreducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis analyses and a glutaraldehyde cross-linking assay suggest that functional AspT forms homo-oligomers as a functional unit.

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