Cell-Free Synthesis of Complex Membrane Proteins

2013 ◽  
pp. 719-738 ◽  
Keyword(s):  
Membrane Proteins ◽  
Complex Membrane

scholarly journals Femtosecond Nanocrystallography and Characterization of Photosystem II

2014 ◽  
Vol 70 (a1) ◽  
pp. C1141-C1141
Author(s):  
Christopher Kupitz ◽  
Shibom Basu ◽  
Ingo Grotjohann ◽  
Raimund Fromme ◽  
Dingjie Wang ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Photosystem Ii ◽  
Conformational Changes ◽  
Perfect Crystal ◽  
Diffusion Method ◽  
Time Resolved ◽  
X Ray Crystallography ◽  
Complex Membrane ◽  
Nonlinear Imaging ◽  
Chiral Crystals

Membrane proteins are extremely difficult to crystallize, however they are highly important proteins for cellular function. Photosystem I, one of the most complex membrane proteins solved to date took more than a decade to have a structure solved to molecular resolution. Large, well-ordered crystal growth is one of the major bottlenecks in structural determination by x-ray crystallography, due to the difficulty of making the "perfect" crystal. The development of femtosecond nanocrystallography, which uses a stream of fully hydrated nanocrystals to collect diffraction snapshots, effectively reduces this bottleneck[1] Photosystem II changed our biosphere via splitting water and evolving oxygen 2.5 billion years ago. Using femtosecond nanocrystallography we are developing a time-resolved femtosecond crystallography method [2] to unravel the mechanism of water splitting by determining the conformational changes that take place during the oxygen evolution process. Multiple crystallization techniques were originally developed in order to make the nanocrystals necessary for femtosecond nanocrystallography. For Photosystem II nano/microcrystals a free interface diffusion method, is used to increase yield over traditional methods. These crystals are then characterized by three different methods before being used for collecting diff raction data. The three methods currently used are optical microscopy, dynamic light scattering (DLS), and Second Order Nonlinear Imaging of Chiral Crystals (SONICC).

scholarly journals Antibody Therapies Targeting Complex Membrane Proteins

Engineering ◽  
2021 ◽  
Author(s):  
Georgina To'a Salazar ◽  
Ziyi Huang ◽  
Ningyan Zhang ◽  
Xue-Guang Zhang ◽  
Zhiqiang An
Keyword(s):  
Membrane Proteins ◽  
Complex Membrane

Multiple topogenic sequences determine the transmembrane orientation of the hepatitis B surface antigen

1987 ◽  
Vol 7 (10) ◽  
pp. 3591-3601
Author(s):  
B E Eble ◽  
D R MacRae ◽  
V R Lingappa ◽  
D Ganem
Keyword(s):  
Membrane Proteins ◽  
Hepatitis B ◽  
Surface Antigen ◽  
Signal Sequence ◽  
Hepatitis B Surface Antigen ◽  
Membrane Topology ◽  
Membrane Bilayer ◽  
Complex Membrane ◽  
Internal Sequence ◽  
Complex Protein

To investigate the mechanism by which complex membrane proteins achieve their correct transmembrane orientation, we examined in detail the hepatitis B surface antigen for sequences which determine its membrane topology. The results demonstrated the presence of at least two kinds of topogenic elements: an N-terminal uncleaved signal sequence and an internal element containing both signal and stop-transfer function. Fusion of reporter groups to either end of the protein suggested that both termini are translocated across the membrane bilayer. We propose that this topology is generated by the conjoint action of both elements and involves a specifically oriented membrane insertion event mediated by the internal sequence. The functional properties of each element can be instructively compared with those of simpler membrane proteins and may provide insight into the generation of other complex protein topologies.

Sequence Analysis of Complex Membrane Proteins (Cytochrome c Oxidase)

1986 ◽  
pp. 340-351 ◽  
Author(s):  
G. Buse ◽  
G. J. Steffens ◽  
G. C. M. Steffens ◽  
L. Meinecke ◽  
S. Hensel ◽  
...  
Keyword(s):  
Sequence Analysis ◽  
Membrane Proteins ◽  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Complex Membrane

scholarly journals Constructing artificial respiratory chain in polymer compartments: Insights into the interplay betweenbo3oxidase and the membrane

2020 ◽  
Vol 117 (26) ◽  
pp. 15006-15017 ◽  
Author(s):  
Nika Marušič ◽  
Lado Otrin ◽  
Ziliang Zhao ◽  
Rafael B. Lira ◽  
Fotis L. Kyrilis ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Transmembrane Protein ◽  
Membrane Properties ◽  
Enzymatic Reactions ◽  
Protein Insertion ◽  
Synthetic Membranes ◽  
Road Map ◽  
Complex Membrane ◽  
Synthetic Cells ◽  
And Control

Cytochromebo3ubiquinol oxidase is a transmembrane protein, which oxidizes ubiquinone and reduces oxygen, while pumping protons. Apart from its combination with F1Fo-ATPase to assemble a minimal ATP regeneration module, the utility of the proton pump can be extended to other applications in the context of synthetic cells such as transport, signaling, and control of enzymatic reactions. In parallel, polymers have been speculated to be phospholipid mimics with respect to their ability to self-assemble in compartments with increased stability. However, their usability as interfaces for complex membrane proteins has remained questionable. In the present work, we optimized a fusion/electroformation approach to reconstitutebo3oxidase in giant unilamellar vesicles made of PDMS-g-PEO and/or phosphatidylcholine (PC). This enabled optical access, while microfluidic trapping allowed for online analysis of individual vesicles. The tight polymer membranes and the inward oriented enzyme caused 1 pH unit difference in 30 min, with an initial rate of 0.35 pH·min−1. To understand the interplay in these composite systems, we studied the relevant mechanical and rheological membrane properties. Remarkably, the proton permeability of polymer/lipid hybrids decreased after protein insertion, while the latter also led to a 20% increase of the polymer diffusion coefficient in polymersomes. In addition, PDMS-g-PEO increased the activity lifetime and the resistance to free radicals. These advantageous properties may open diverse applications, ranging from cell-free biotechnology to biomedicine. Furthermore, the presented study serves as a comprehensive road map for studying the interactions between membrane proteins and synthetic membranes, which will be fundamental for the successful engineering of such hybrid systems.

Proteopedia entry: Structure of complex membrane proteins solved using cryo‐ electron microscopy

2021 ◽  
Author(s):  
R. Jeremy Johnson ◽  
Grace Bassler ◽  
Emma Harris ◽  
Ryan Heumann ◽  
Abby Hillan ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Membrane Proteins ◽  
Cryo Electron Microscopy ◽  
Complex Membrane

Nanoscopic leg irons: harvesting of polymer-stabilized membrane proteins with antibody-functionalized silica nanoparticles

2015 ◽  
Vol 3 (9) ◽  
pp. 1279-1283 ◽  
Author(s):  
Thomas Zapf ◽  
Christian Zafiu ◽  
Christoph Zaba ◽  
Cherng-Wen Darren Tan ◽  
Walter Hunziker ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Membrane Proteins ◽  
Silica Nanoparticles ◽  
Functionalized Silica ◽  
Complex Membrane ◽  
Polymer Stabilized ◽  
Functionalized Silica Nanoparticles

Silica-based nanoparticles (SiNPs) are presented to harvest complex membrane proteins, which have been embedded into unilammelar polymersomes via membrane assisted protein synthesis (iMAP).

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