scholarly journals Reconstitution of the membrane protein OmpF into biomimetic block copolymer–phospholipid hybrid membranes

2016 ◽  
Vol 7 ◽  
pp. 881-892 ◽  
Author(s):  
Matthias Bieligmeyer ◽  
Franjo Artukovic ◽  
Stephan Nussberger ◽  
Thomas Hirth ◽  
Thomas Schiestel ◽  
...  
Keyword(s):  
Block Copolymers ◽  
Membrane Protein ◽  
Protein Function ◽  
Transmembrane Proteins ◽  
Synthetic Polymer ◽  
Structure And Function ◽  
Membrane Thickness ◽  
Channel Conductance ◽  
Biomimetic Polymer ◽  
And Function

Structure and function of many transmembrane proteins are affected by their environment. In this respect, reconstitution of a membrane protein into a biomimetic polymer membrane can alter its function. To overcome this problem we used membranes formed by poly(1,4-isoprene-block-ethylene oxide) block copolymers blended with 1,2-diphytanoyl-sn-glycero-3-phosphocholine. By reconstituting the outer membrane protein OmpF from Escherichia coli into these membranes, we demonstrate functionality of this protein in biomimetic lipopolymer membranes, independent of the molecular weight of the block copolymers. At low voltages, the channel conductance of OmpF in 1 M KCl was around 2.3 nS. In line with these experiments, integration of OmpF was also revealed by impedance spectroscopy. Our results indicate that blending synthetic polymer membranes with phospholipids allows for the reconstitution of transmembrane proteins under preservation of protein function, independent of the membrane thickness.

Order-disorder transitions of cytoplasmic N-termini in the mechanisms of P-type ATPases

2020 ◽  
Author(s):  
Khondker Rufaka Hossain ◽  
Daniel Clayton ◽  
Sophia C Goodchild ◽  
Alison Rodger ◽  
Richard James Payne ◽  
...  
Keyword(s):  
Protein Structure ◽  
Membrane Protein ◽  
Structure And Function ◽  
Membrane Protein Structure ◽  
Protein Structure And Function ◽  
Lipid Environment ◽  
Membrane Pumps ◽  
And Function ◽  
P Type

Membrane protein structure and function are modulated via interactions with their lipid environment. This is particularly true for the integral membrane pumps, the P-type ATPases. These ATPases play vital roles...

Nanoscale lipid membrane mimetics in spin-labeling and electron paramagnetic resonance spectroscopy studies of protein structure and function

2017 ◽  
Vol 6 (1) ◽  
pp. 75-92 ◽  
Author(s):  
Elka R. Georgieva
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Protein Structure ◽  
Membrane Proteins ◽  
Membrane Protein ◽  
Spin Labeling ◽  
Structure And Function ◽  
Protein Structure And Function ◽  
Paramagnetic Resonance ◽  
And Function ◽  
Electron Paramagnetic

AbstractCellular membranes and associated proteins play critical physiological roles in organisms from all life kingdoms. In many cases, malfunction of biological membranes triggered by changes in the lipid bilayer properties or membrane protein functional abnormalities lead to severe diseases. To understand in detail the processes that govern the life of cells and to control diseases, one of the major tasks in biological sciences is to learn how the membrane proteins function. To do so, a variety of biochemical and biophysical approaches have been used in molecular studies of membrane protein structure and function on the nanoscale. This review focuses on electron paramagnetic resonance with site-directed nitroxide spin-labeling (SDSL EPR), which is a rapidly expanding and powerful technique reporting on the local protein/spin-label dynamics and on large functionally important structural rearrangements. On the other hand, adequate to nanoscale study membrane mimetics have been developed and used in conjunction with SDSL EPR. Primarily, these mimetics include various liposomes, bicelles, and nanodiscs. This review provides a basic description of the EPR methods, continuous-wave and pulse, applied to spin-labeled proteins, and highlights several representative applications of EPR to liposome-, bicelle-, or nanodisc-reconstituted membrane proteins.

scholarly journals In silico prediction of structure and function for a large family of transmembrane proteins that includes human Tmem41b

F1000Research ◽  
2020 ◽  
Vol 9 ◽  
pp. 1395
Author(s):  
Shahram Mesdaghi ◽  
David L. Murphy ◽  
Filomeno Sánchez Rodríguez ◽  
J. Javier Burgos-Mármol ◽  
Daniel J. Rigden
Keyword(s):  
Ab Initio ◽  
Rotational Symmetry ◽  
Domain Boundary ◽  
Pfam Domain ◽  
Transmembrane Proteins ◽  
Large Family ◽  
Data Bank ◽  
Structural Features ◽  
Structure And Function ◽  
And Function

Background: Recent strides in computational structural biology have opened up an opportunity to understand previously uncharacterised proteins.  The under-representation of transmembrane proteins in the Protein Data Bank highlights the need to apply new and advanced bioinformatics methods to shed light on their structure and function.  This study focuses on a family of transmembrane proteins containing the Pfam domain PF09335 ('SNARE_ASSOC'/ ‘VTT ‘/’Tvp38’). One prominent member, Tmem41b, has been shown to be involved in early stages of autophagosome formation and is vital in mouse embryonic development as well as being identified as a viral host factor of SARS-CoV-2. Methods: We used evolutionary covariance-derived information to construct and validate ab initio models, make domain boundary predictions and infer local structural features.  Results: The results from the structural bioinformatics analysis of Tmem41b and its homologues showed that they contain a tandem repeat that is clearly visible in evolutionary covariance data but much less so by sequence analysis.  Furthermore, cross-referencing of other prediction data with covariance analysis showed that the internal repeat features two-fold rotational symmetry.  Ab initio modelling of Tmem41b and homologues reinforces these structural predictions.  Local structural features predicted to be present in Tmem41b were also present in Cl-/H+ antiporters.  Conclusions: The results of this study strongly point to Tmem41b and its homologues being transporters for an as-yet uncharacterised substrate and possibly using H+ antiporter activity as its mechanism for transport.

scholarly journals Primary structure and function of a cytotoxic outer-membrane protein (ComP) of Plesiomonas shigelloides

2008 ◽  
Vol 281 (1) ◽  
pp. 10-16 ◽  
Author(s):  
Hitoshi Tsugawa ◽  
Asako Ogawa ◽  
Satomi Takehara ◽  
Mayumi Kimura ◽  
Yoshio Okawa
Keyword(s):  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Primary Structure ◽  
Structure And Function ◽  
Plesiomonas Shigelloides ◽  
And Function

scholarly journals Aim24 and MICOS modulate respiratory function, tafazzin-related cardiolipin modification and mitochondrial architecture

eLife ◽  
2014 ◽  
Vol 3 ◽  
Author(s):  
Max Emanuel Harner ◽  
Ann-Katrin Unger ◽  
Toshiaki Izawa ◽  
Dirk M Walther ◽  
Cagakan Özbalci ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Respiratory Function ◽  
Structure And Function ◽  
Complete Loss ◽  
Mitochondrial Ultrastructure ◽  
Inner Membrane ◽  
Outer Membranes ◽  
Contact Sites ◽  
Inner Membrane Protein ◽  
And Function

Structure and function of mitochondria are intimately linked. In a search for components that participate in building the elaborate architecture of this complex organelle we have identified Aim24, an inner membrane protein. Aim24 interacts with the MICOS complex that is required for the formation of crista junctions and contact sites between inner and outer membranes. Aim24 is necessary for the integrity of the MICOS complex, for normal respiratory growth and mitochondrial ultrastructure. Modification of MICOS subunits Mic12 or Mic26 by His-tags in the absence of Aim24 leads to complete loss of cristae and respiratory complexes. In addition, the level of tafazzin, a cardiolipin transacylase, is drastically reduced and the composition of cardiolipin is modified like in mutants lacking tafazzin. In conclusion, Aim24 by interacting with the MICOS complex plays a key role in mitochondrial architecture, composition and function.

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