scholarly journals The C-terminal tail guides assembly and degradation of membrane proteins

2019 ◽  
Author(s):  
Sha Sun ◽  
Malaiyalam Mariappan
Keyword(s):  
Quality Control ◽  
Endoplasmic Reticulum ◽  
Membrane Proteins ◽  
Membrane Protein ◽  
Nuclear Membrane ◽  
Time Window ◽  
Protein Complexes ◽  
Long Tails ◽  
Membrane Protein Complexes ◽  
Biochemical Features

SUMMARYA large number of newly synthesized membrane proteins in the endoplasmic reticulum (ER) are assembled into multi-protein complexes, but little is known about the mechanisms required for either assembly or degradation of unassembled membrane proteins. We find that C-terminal transmembrane domains (C-TMDs) with shorter tails are inefficiently inserted into the ER membrane since the translation is terminated before they emerge from ribosomes. These TMDs of insufficient hydrophobicity are post-translationally retained by the Sec61 translocon, thus providing a time window for efficient assembly with TMDs from partner membrane proteins. The unassembled C-TMDs are slowly flipped into the ER lumen. While the luminal chaperone BiP captures flipped C-TMDs with long tails and routes them to the ER-associated quality control, C-TMDs with shorter tails are diffused into the nuclear membrane. Thus, our studies suggest that C-terminal tails harbor important biochemical features for both biosynthesis and quality control of membrane protein complexes.

Three-dimensional crystallization of membrane proteins

1988 ◽  
Vol 21 (4) ◽  
pp. 429-477 ◽  
Author(s):  
W. Kühlbrandt
Keyword(s):  
High Resolution ◽  
Membrane Proteins ◽  
Membrane Protein ◽  
Protein Complexes ◽  
Three Dimensional ◽  
Biological Macromolecules ◽  
X Ray ◽  
X Ray Crystallography ◽  
Membrane Protein Complexes ◽  
Essential Prerequisite

As recently as 10 years ago, the prospect of solving the structure of any membrane protein by X-ray crystallography seemed remote. Since then, the threedimensional (3-D) structures of two membrane protein complexes, the bacterial photosynthetic reaction centres of Rhodopseudomonas viridis (Deisenhofer et al. 1984, 1985) and of Rhodobacter sphaeroides (Allen et al. 1986, 1987 a, 6; Chang et al. 1986) have been determined at high resolution. This astonishing progress would not have been possible without the pioneering work of Michel and Garavito who first succeeded in growing 3-D crystals of the membrane proteins bacteriorhodopsin (Michel & Oesterhelt, 1980) and matrix porin (Garavito & Rosenbusch, 1980). X-ray crystallography is still the only routine method for determining the 3-D structures of biological macromolecules at high resolution and well-ordered 3-D crystals of sufficient size are the essential prerequisite.

scholarly journals YidC family members are involved in the membrane insertion, lateral integration, folding, and assembly of membrane proteins

2004 ◽  
Vol 166 (6) ◽  
pp. 769-774 ◽  
Author(s):  
Ross E. Dalbey ◽  
Andreas Kuhn
Keyword(s):  
Membrane Proteins ◽  
Membrane Protein ◽  
Protein Complexes ◽  
Family Members ◽  
Membrane Insertion ◽  
Conducting Channel ◽  
Energy Devices ◽  
Domains Of Life ◽  
Membrane Protein Complexes ◽  
Sensor Proteins

Members of the YidC family exist in all three domains of life, where they control the assembly of a large variety of membrane protein complexes that function as transporters, energy devices, or sensor proteins. Recent studies in bacteria have shown that YidC functions on its own as a membrane protein insertase independent of the Sec protein–conducting channel. YidC can also assist in the lateral integration and folding of membrane proteins that insert into the membrane via the Sec pathway.

scholarly journals Evidence for Membrane Complex Assembly in Nanoelectrospray Generated Lipid Bilayers

2019 ◽  
Author(s):  
Matthias Wilm
Keyword(s):  
Membrane Proteins ◽  
Membrane Protein ◽  
Lipid Bilayers ◽  
Layered Structure ◽  
Protein Complexes ◽  
Complex Assembly ◽  
Membrane Complex ◽  
Detergent Extraction ◽  
Membrane Protein Complexes

1.AbstractNanoelectrospray can be used to generate a layered structure consisting of bipolar lipids, detergent-solubilized membrane proteins, and glycerol that self-assembles upon detergent extraction into one extended layer of a protein containing membrane. This manuscript presents the first evidence that this method might allow membrane protein complexes to assemble in this process.

scholarly journals New approach for membrane protein reconstitution into peptidiscs and basis for their adaptability to different proteins

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Gabriella Angiulli ◽  
Harveer Singh Dhupar ◽  
Hiroshi Suzuki ◽  
Irvinder Singh Wason ◽  
Franck Duong Van Hoa ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Membrane Protein ◽  
Protein Complexes ◽  
Structural Basis ◽  
New Approach ◽  
Functional Studies ◽  
Cryo Electron Microscopy ◽  
High Resolution Structure ◽  
Membrane Protein Complexes ◽  
Membrane Protein Reconstitution

Previously we introduced peptidiscs as an alternative to detergents to stabilize membrane proteins in solution (Carlson et al., 2018). Here, we present ‘on-gradient’ reconstitution, a new gentle approach for the reconstitution of labile membrane-protein complexes, and used it to reconstitute Rhodobacter sphaeroides reaction center complexes, demonstrating that peptidiscs can adapt to transmembrane domains of very different sizes and shapes. Using the conventional ‘on-bead’ approach, we reconstituted Escherichia coli proteins MsbA and MscS and find that peptidiscs stabilize them in their native conformation and allow for high-resolution structure determination by cryo-electron microscopy. The structures reveal that peptidisc peptides can arrange around transmembrane proteins differently, thus revealing the structural basis for why peptidiscs can stabilize such a large variety of membrane proteins. Together, our results establish the gentle and easy-to-use peptidiscs as a potentially universal alternative to detergents as a means to stabilize membrane proteins in solution for structural and functional studies.

scholarly journals Mass spectrometry of membrane protein complexes

2019 ◽  
Vol 400 (7) ◽  
pp. 813-829 ◽  
Author(s):  
Julian Bender ◽  
Carla Schmidt
Keyword(s):  
Mass Spectrometry ◽  
Membrane Proteins ◽  
Membrane Protein ◽  
Protein Complexes ◽  
Three Dimensional ◽  
Membrane Protein Complexes ◽  
Hydrophobic Nature ◽  
Alternative Approaches ◽  
Lipid Environment ◽  
And Function

Abstract Membrane proteins are key players in the cell. Due to their hydrophobic nature they require solubilising agents such as detergents or membrane mimetics during purification and, consequently, are challenging targets in structural biology. In addition, their natural lipid environment is crucial for their structure and function further hampering their analysis. Alternative approaches are therefore required when the analysis by conventional techniques proves difficult. In this review, we highlight the broad application of mass spectrometry (MS) for the characterisation of membrane proteins and their interactions with lipids. We show that MS unambiguously identifies the protein and lipid components of membrane protein complexes, unravels their three-dimensional arrangements and further provides clues of protein-lipid interactions.

scholarly journals The Escherichia coli Membrane Protein Insertase YidC Assists in the Biogenesis of Penicillin Binding Proteins

2015 ◽  
Vol 197 (8) ◽  
pp. 1444-1450 ◽  
Author(s):  
Anabela de Sousa Borges ◽  
Jeanine de Keyzer ◽  
Arnold J. M. Driessen ◽  
Dirk-Jan Scheffers
Keyword(s):  
Escherichia Coli ◽  
Membrane Proteins ◽  
Membrane Protein ◽  
Binding Proteins ◽  
Protein Complexes ◽  
Specific Cell ◽  
Similar Reduction ◽  
Penicillin Binding Proteins ◽  
Membrane Protein Complexes ◽  
Sec Translocon

ABSTRACTMembrane proteins need to be properly inserted and folded in the membrane in order to perform a range of activities that are essential for the survival of bacteria. The Sec translocon and the YidC insertase are responsible for the insertion of the majority of proteins into the cytoplasmic membrane. YidC can act in combination with the Sec translocon in the insertion and folding of membrane proteins. However, YidC also functions as an insertase independently of the Sec translocon for so-called YidC-only substrates. In addition, YidC can act as a foldase and promote the proper assembly of membrane protein complexes. Here, we investigate the effect ofEscherichia coliYidC depletion on the assembly of penicillin binding proteins (PBPs), which are involved in cell wall synthesis. YidC depletion does not affect the total amount of the specific cell division PBP3 (FtsI) in the membrane, but the amount of active PBP3, as assessed by substrate binding, is reduced 2-fold. A similar reduction in the amount of active PBP2 was observed, while the levels of active PBP1A/1B and PBP5 were essentially similar. PBP1B and PBP3 disappeared from higher-Mwbands upon YidC depletion, indicating that YidC might play a role in PBP complex formation. Taken together, our results suggest that the foldase activity of YidC can extend to the periplasmic domains of membrane proteins.IMPORTANCEThis study addresses the role of the membrane protein insertase YidC in the biogenesis of penicillin binding proteins (PBPs). PBPs are proteins containing one transmembrane segment and a large periplasmic or extracellular domain, which are involved in peptidoglycan synthesis. We observe that in the absence of YidC, two critical PBPs are not correctly folded even though the total amount of protein in the membrane is not affected. Our findings extend the function of YidC as a foldase for membrane protein (complexes) to periplasmic domains of membrane proteins.

scholarly journals C-terminal tail length guides insertion and assembly of membrane proteins

2020 ◽  
Vol 295 (46) ◽  
pp. 15498-15510 ◽  
Author(s):  
Sha Sun ◽  
Malaiyalam Mariappan
Keyword(s):  
Amino Acids ◽  
Endoplasmic Reticulum ◽  
Membrane Proteins ◽  
Molecular Chaperones ◽  
Time Window ◽  
Protein Complexes ◽  
Tail Length ◽  
Protein Components ◽  
Partner Proteins ◽  
Erad Pathway

A large number of newly synthesized membrane proteins in the endoplasmic reticulum (ER) are assembled into multiprotein complexes, but little is known about the mechanisms required for assembly membrane proteins. It has been suggested that membrane chaperones might exist, akin to the molecular chaperones that stabilize and direct the assembly of soluble protein complexes, but the mechanisms by which these proteins would bring together membrane protein components is unclear. Here, we have identified that the tail length of the C-terminal transmembrane domains (C-TMDs) determines efficient insertion and assembly of membrane proteins in the ER. We found that membrane proteins with C-TMD tails shorter than ∼60 amino acids are poorly inserted into the ER membrane, which suggests that translation is terminated before they are recognized by the Sec61 translocon for insertion. These C-TMDs with insufficient hydrophobicity are post-translationally recognized and retained by the Sec61 translocon complex, providing a time window for efficient assembly with TMDs from partner proteins. Retained TMDs that fail to assemble with their cognate TMDs are slowly translocated into the ER lumen and are recognized by the ER-associated degradation (ERAD) pathway for removal. In contrast, C-TMDs with sufficient hydrophobicity or tails longer than ∼80 residues are quickly released from the Sec61 translocon into the membrane or the ER lumen, resulting in inefficient assembly with partner TMDs. Thus, our data suggest that C-terminal tails harbor crucial signals for both the insertion and assembly of membrane proteins.

scholarly journals Native mass spectrometry goes more native: investigation of membrane protein complexes directly from SMALPs

2018 ◽  
Vol 54 (97) ◽  
pp. 13702-13705 ◽  
Author(s):  
Nils Hellwig ◽  
Oliver Peetz ◽  
Zainab Ahdash ◽  
Igor Tascón ◽  
Paula J. Booth ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Membrane Proteins ◽  
Membrane Protein ◽  
Lipid Bilayer ◽  
Maleic Acid ◽  
Protein Complexes ◽  
Native Mass Spectrometry ◽  
Direct Extraction ◽  
Membrane Protein Complexes

Other than more widely used methods, the use of styrene maleic acid copolymers allows the direct extraction of membrane proteins from the lipid bilayer into SMALPs keeping it in its native lipid surrounding.

scholarly journals Signal peptide peptidase (SPP) assembles with substrates and misfolded membrane proteins into distinct oligomeric complexes

2010 ◽  
Vol 427 (3) ◽  
pp. 523-534 ◽  
Author(s):  
Bianca Schrul ◽  
Katja Kapp ◽  
Irmgard Sinning ◽  
Bernhard Dobberstein
Keyword(s):  
Quality Control ◽  
Endoplasmic Reticulum ◽  
Membrane Proteins ◽  
Membrane Protein ◽  
Signal Peptide ◽  
Large Range ◽  
Endoplasmic Reticulum Membrane ◽  
Signal Peptides ◽  
Type Ii ◽  
Signal Peptide Peptidase

SPP (signal peptide peptidase) is an aspartyl intramembrane cleaving protease, which processes a subset of signal peptides, and is linked to the quality control of ER (endoplasmic reticulum) membrane proteins. We analysed SPP interactions with signal peptides and other membrane proteins by co-immunoprecipitation assays. We found that SPP interacts specifically and tightly with a large range of newly synthesized membrane proteins, including signal peptides, preproteins and misfolded membrane proteins, but not with all co-expressed type II membrane proteins. Signal peptides are trapped by the catalytically inactive SPP mutant SPPD/A. Preproteins and misfolded membrane proteins interact with both SPP and the SPPD/A mutant, and are not substrates for SPP-mediated intramembrane proteolysis. Proteins interacting with SPP are found in distinct complexes of different sizes. A signal peptide is mainly trapped in a 200 kDa SPP complex, whereas a preprotein is predominantly found in a 600 kDa SPP complex. A misfolded membrane protein is detected in 200, 400 and 600 kDa SPP complexes. We conclude that SPP not only processes signal peptides, but also collects preproteins and misfolded membrane proteins that are destined for disposal.

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