Search results for "Transmembrane protein"

Nitrated Fatty Acids Modulate the Physical Properties of Model Membranes and the Structure of Transmembrane Proteins

2017

Nitrated fatty acids (NO2 -FAs) act as anti-inflammatory signal mediators, albeit the molecular mechanisms behind NO2 -FAs' influence on diverse metabolic and signaling pathways in inflamed tissues are essentially elusive. Here, we combine fluorescence measurements with surface-specific sum frequency generation vibrational spectroscopy and coarse-grained computer simulations to demonstrate that NO2 -FAs alter lipid organization by accumulation at the membrane-water interface. As the function of membrane proteins strongly depends on both, protein structure as well as membrane properties, we consecutively follow the structural dynamics of an integral membrane protein in presence of NO2 -FAs. …

2018

Tetraspanins (Tspans) are a family of four-span transmembrane proteins, known as plasma membrane “master organizers.” They form Tspan-enriched microdomains (TEMs or TERMs) through lateral association with one another and other membrane proteins. If multiple microdomains associate with each other, larger platforms can form. For infection, viruses interact with multiple cell surface components, including receptors, activating proteases, and signaling molecules. It appears that Tspans, such as CD151, CD82, CD81, CD63, CD9, Tspan9, and Tspan7, coordinate these associations by concentrating the interacting partners into Tspan platforms. In addition to mediating viral attachment and entry, these …

A genomic reappraisal of symbiotic function in the aphid/Buchnera symbiosis: reduced transporter sets and variable membrane organisations.

2011

International audience; Buchnera aphidicola is an obligate symbiotic bacterium that sustains the physiology of aphids by complementing their exclusive phloem sap diet. In this study, we reappraised the transport function of different Buchnera strains, from the aphids Acyrthosiphon pisum, Schizaphis graminum, Baizongia pistaciae and Cinara cedri, using the re-annotation of their transmembrane proteins coupled with an exploration of their metabolic networks. Although metabolic analyses revealed high interdependencies between the host and the bacteria, we demonstrate here that transport in Buchnera is assured by low transporter diversity, when compared to free-living bacteria, being mostly bas…

Interactions of membranes with coarse-grain proteins: a comparison

2012

We study the interactions between lipid bilayers and rigid transmembrane proteins by Monte Carlo simulations of generic coarse-grain models. Different popular protein models are considered and compared with each other, and key parameters such as the hydrophobicity and the hydrophobic mismatch are varied systematically. Furthermore, the properties of the membrane are manipulated by applying different tensions. The response of the membrane to the insertion of single proteins is found to be mostly generic and independent of the choice of the protein model. Likewise, the orientational distributions of single proteins depend mainly on the hydrophobic mismatch and the hydrophobicity of the protei…

Properties of transmembrane helix TM1 of the DcuS sensor kinase of Escherichia coli, the stator for TM2 piston signaling

2021

Abstract The sensor kinase DcuS of Escherichia coli perceives extracellular fumarate by a periplasmic PASP sensor domain. Transmembrane (TM) helix TM2, present as TM2-TM2′ homo-dimer, transmits fumarate activation in a piston-slide across the membrane. The second TM helix of DcuS, TM1, is known to lack piston movement. Structural and functional properties of TM1 were analyzed. Oxidative Cys-crosslinking (CL) revealed homo-dimerization of TM1 over the complete membrane, but only the central part showed α-helical +3/+4 spacing of the CL maxima. The GALLEX bacterial two-hybrid system indicates TM1/TM1′ interaction, and the presence of a TM1-TM1′ homo-dimer is suggested. The peripheral TM1 regi…

Lipid Binding Controls Dimerization of the Coat Protein p24 Transmembrane Helix

2019

Abstract Coat protein (COP) I and COP II complexes are involved in the transport of proteins between the endoplasmic reticulum and the Golgi apparatus in eukaryotic cells. The formation of COP I/II complexes at membrane surfaces is an early step in vesicle formation and is mastered by p24, a type I transmembrane protein. Oligomerization of p24 monomers was suggested to be mediated and/or stabilized via interactions within the transmembrane domain, and the p24 transmembrane helix appears to selectively bind a single sphingomyelin C18:0 molecule. Furthermore, a potential cholesterol-binding sequence has also been predicted in the p24 transmembrane domain. Thus, sphingomyelin and/or cholestero…