Structure and function of integral membrane protein domains resolved by peptide-amphiphiles: Application to phospholamban

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...

Download Full-text

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

Nanotechnology Reviews ◽

10.1515/ntrev-2016-0080 ◽

2017 ◽

Vol 6 (1) ◽

pp. 75-92 ◽

Cited By ~ 6

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.

Download Full-text

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

Beilstein Journal of Nanotechnology ◽

10.3762/bjnano.7.80 ◽

2016 ◽

Vol 7 ◽

pp. 881-892 ◽

Cited By ~ 7

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.

Download Full-text

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

FEMS Microbiology Letters ◽

10.1111/j.1574-6968.2007.01041.x ◽

2008 ◽

Vol 281 (1) ◽

pp. 10-16 ◽

Cited By ~ 5

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

Download Full-text

Structure and function of mitochondrial membrane protein complexes

BMC Biology ◽

10.1186/s12915-015-0201-x ◽

2015 ◽

Vol 13 (1) ◽

Cited By ~ 169

Author(s):

Werner Kühlbrandt

Keyword(s):

Membrane Protein ◽

Mitochondrial Membrane ◽

Protein Complexes ◽

Structure And Function ◽

Membrane Protein Complexes ◽

And Function ◽

Mitochondrial Membrane Protein

Download Full-text

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

eLife ◽

10.7554/elife.01684 ◽

2014 ◽

Vol 3 ◽

Cited By ~ 48

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.

Download Full-text

A previously unrecognized membrane protein in the Rhodobacter sphaeroides LH1-RC photocomplex

Nature Communications ◽

10.1038/s41467-021-26561-9 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Kazutoshi Tani ◽

Kenji V. P. Nagashima ◽

Ryo Kanno ◽

Saki Kawamura ◽

Riku Kikuchi ◽

...

Keyword(s):

Membrane Protein ◽

Ring Opening ◽

Model Organism ◽

Hypothetical Protein ◽

Integral Membrane Protein ◽

Bacterial Photosynthesis ◽

Core Complex ◽

Rc Structures ◽

Complex Forms ◽

And Function

AbstractRhodobacter (Rba.) sphaeroides is the most widely used model organism in bacterial photosynthesis. The light-harvesting-reaction center (LH1-RC) core complex of this purple phototroph is characterized by the co-existence of monomeric and dimeric forms, the presence of the protein PufX, and approximately two carotenoids per LH1 αβ-polypeptides. Despite many efforts, structures of the Rba. sphaeroides LH1-RC have not been obtained at high resolutions. Here we report a cryo-EM structure of the monomeric LH1-RC from Rba. sphaeroides strain IL106 at 2.9 Å resolution. The LH1 complex forms a C-shaped structure composed of 14 αβ-polypeptides around the RC with a large ring opening. From the cryo-EM density map, a previously unrecognized integral membrane protein, referred to as protein-U, was identified. Protein-U has a U-shaped conformation near the LH1-ring opening and was annotated as a hypothetical protein in the Rba. sphaeroides genome. Deletion of protein-U resulted in a mutant strain that expressed a much-reduced amount of the dimeric LH1-RC, indicating an important role for protein-U in dimerization of the LH1-RC complex. PufX was located opposite protein-U on the LH1-ring opening, and both its position and conformation differed from that of previous reports of dimeric LH1-RC structures obtained at low-resolution. Twenty-six molecules of the carotenoid spheroidene arranged in two distinct configurations were resolved in the Rba. sphaeroides LH1 and were positioned within the complex to block its channels. Our findings offer an exciting new view of the core photocomplex of Rba. sphaeroides and the connections between structure and function in bacterial photocomplexes in general.

Download Full-text

A Novel Membrane Protein in the Rhodobacter sphaeroides LH1-RC Photocomplex

10.1101/2021.06.20.449127 ◽

2021 ◽

Author(s):

K. Tani ◽

K. V. P. Nagashima ◽

R. Kanno ◽

S. Kawamura ◽

R. Kikuchi ◽

...

Keyword(s):

Membrane Protein ◽

Ring Opening ◽

Hypothetical Protein ◽

Integral Membrane Protein ◽

Purple Bacterium ◽

Core Complex ◽

Rc Structures ◽

Density Map ◽

Complex Forms ◽

And Function

We present a cryo-EM structure of the monomeric light-harvesting-reaction center (LH1-RC) core complex from photosynthetic purple bacterium Rhodobacter (Rba.) sphaeroides at 2.9 Å resolution. The LH1 complex forms a C-shaped structure composed of 14 αβ-polypeptides around the RC with a large ring opening. From the cryo-EM density map, a previously unrecognized integral membrane protein, referred to as protein-U, was identified. Protein-U has a U-shaped conformation near the LH1-ring opening and was annotated as a hypothetical protein in the Rba. sphaeroides genome. Deletion of protein-U resulted in a mutant strain that expressed a much-reduced amount of the dimeric LH1-RC, indicating an important role for protein-U in dimerization of the LH1-RC complex. PufX was located opposite protein-U on the LH1-ring opening, and both its position and conformation differed from that of previous reports of dimeric LH1-RC structures obtained at low-resolution. Twenty-six molecules of the carotenoid spheroidene arranged in two distinct configurations were resolved in the Rba. sphaeroides LH1 and were positioned within the complex to block its pores. Our findings offer a new view of the core photocomplex of Rba. sphaeroides and the connections between structure and function in bacterial photocomplexes in general.

Download Full-text