A transmembrane serine residue in the Rot1 protein is essential for yeast cell viability

2014 ◽  
Vol 458 (2) ◽  
pp. 239-249 ◽  
Author(s):  
Carlos A. Martínez-Garay ◽  
M. Angeles Juanes ◽  
J. Carlos Igual ◽  
Ismael Mingarro ◽  
M. Carmen Bañó
Keyword(s):  
Amino Acids ◽  
Cell Death ◽  
Membrane Proteins ◽  
Membrane Protein ◽  
Cell Viability ◽  
Yeast Cell ◽  
Protein Function ◽  
Transmembrane Domain ◽  
Transmembrane Helices ◽  
Serine Residue

Polar residues present in transmembrane helices influence the folding or association of membrane proteins. Rot1 is a membrane protein with a single transmembrane domain. Replacement of a serine residue in the transmembrane domain by different amino acids precluded protein function, causing cell death.

scholarly journals Energetics of side-chain snorkeling in transmembrane helices probed by nonproteinogenic amino acids

2016 ◽  
Vol 113 (38) ◽  
pp. 10559-10564 ◽  
Author(s):  
Karin Öjemalm ◽  
Takashi Higuchi ◽  
Patricia Lara ◽  
Erik Lindahl ◽  
Hiroaki Suga ◽  
...  
Keyword(s):  
Amino Acids ◽  
Membrane Protein ◽  
Side Chain ◽  
Transmembrane Helices ◽  
Transmembrane Segments ◽  
Charged Amino Acids ◽  
Protein Biogenesis ◽  
Quantitative Basis ◽  
Apparent Free Energy ◽  
Integration Efficiency

Cotranslational translocon-mediated insertion of membrane proteins into the endoplasmic reticulum is a key process in membrane protein biogenesis. Although the mechanism is understood in outline, quantitative data on the energetics of the process is scarce. Here, we have measured the effect on membrane integration efficiency of nonproteinogenic analogs of the positively charged amino acids arginine and lysine incorporated into model transmembrane segments. We provide estimates of the influence on the apparent free energy of membrane integration (ΔGapp) of “snorkeling” of charged amino acids toward the lipid–water interface, and of charge neutralization. We further determine the effect of fluorine atoms and backbone hydrogen bonds (H-bonds) on ΔGapp. These results help establish a quantitative basis for our understanding of membrane protein assembly in eukaryotic cells.

scholarly journals A Survey of Membrane Proteins in Human Serum

2012 ◽  
Vol 5 ◽  
pp. PRI.S9374 ◽  
Author(s):  
Nguyen Tien Dung ◽  
Phan Van Chi
Keyword(s):  
Membrane Proteins ◽  
Membrane Protein ◽  
Human Serum ◽  
Transmembrane Domain ◽  
Tissue Sample ◽  
Ionization Mass ◽  
Post Translational Modifications ◽  
Molecular Weights ◽  
Normal Human ◽  
Nano Liquid Chromatography

Serum and membrane proteins are two of the most attractive targets for proteomic analysis. Previous membrane protein studies tend to focus on tissue sample, while membrane protein studies in serum are still limited. In this study, an analysis of membrane proteins in normal human serum was carried out. Nano-liquid chromatography-electrospray ionization mass spectrometry (NanoLC-ESI-MS/MS) and bioinformatics tools were used to identify membrane proteins. Two hundred and seventeen membrane proteins were detected in the human serum, of which 129 membrane proteins have at least one transmembrane domain (TMD). Further characterizations of identified membrane proteins including their subcellular distributions, molecular weights, post translational modifications, transmembrane domains and average of hydrophobicity, were also implemented. Our results showed the potential of membrane proteins in serum for diagnosis and treatment of diseases.

scholarly journals Canine Distemper Virus and Measles Virus Fusion Glycoprotein Trimers: Partial Membrane-Proximal Ectodomain Cleavage Enhances Function

2004 ◽  
Vol 78 (15) ◽  
pp. 7894-7903 ◽  
Author(s):  
Veronika von Messling ◽  
Dragana Milosevic ◽  
Patricia Devaux ◽  
Roberto Cattaneo
Keyword(s):  
Amino Acids ◽  
Protein Function ◽  
Measles Virus ◽  
Canine Distemper Virus ◽  
Transmembrane Domain ◽  
Fusion Pore ◽  
Canine Distemper ◽  
Furin Cleavage ◽  
F Protein ◽  
Membrane Processing

ABSTRACT The trimeric fusion (F) glycoproteins of morbilliviruses are activated by furin cleavage of the precursor F0 into the F1 and F2 subunits. Here we show that an additional membrane-proximal cleavage occurs and modulates F protein function. We initially observed that the ectodomain of approximately one in three measles virus (MV) F proteins is cleaved proximal to the membrane. Processing occurs after cleavage activation of the precursor F0 into the F1 and F2 subunits, producing F1a and F1b fragments that are incorporated in viral particles. We also detected the F1b fragment, including the transmembrane domain and cytoplasmic tail, in cells expressing the canine distemper virus (CDV) or mumps virus F protein. Six membrane-proximal amino acids are necessary for efficient CDV F1a/b cleavage. These six amino acids can be exchanged with the corresponding MV F protein residues of different sequence without compromising function. Thus, structural elements of different sequence are functionally exchangeable. Finally, we showed that the alteration of a block of membrane-proximal amino acids results in diminished fusion activity in the context of a recombinant CDV. We envisage that selective loss of the membrane anchor in the external subunits of circularly arranged F protein trimers may disengage them from pulling the membrane centrifugally, thereby facilitating fusion pore formation.

scholarly journals Tail-Anchored Inner Membrane Protein ElaB Increases Resistance to Stress While Reducing Persistence in Escherichia coli

2017 ◽  
Vol 199 (9) ◽  
Author(s):  
Yunxue Guo ◽  
Xiaoxiao Liu ◽  
Baiyuan Li ◽  
Jianyun Yao ◽  
Thomas K. Wood ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Escherichia Coli ◽  
Membrane Proteins ◽  
Membrane Protein ◽  
Stationary Phase ◽  
Transmembrane Domain ◽  
Inner Membrane ◽  
Content Type ◽  
E Coli ◽  
Inner Membrane Protein

ABSTRACT Host-associated bacteria, such as Escherichia coli, often encounter various host-related stresses, such as nutritional deprivation, oxidative stress, and temperature shifts. There is growing interest in searching for small endogenous proteins that mediate stress responses. Here, we characterized the small C-tail-anchored inner membrane protein ElaB in E. coli. ElaB belongs to a class of tail-anchored inner membrane proteins with a C-terminal transmembrane domain but lacking an N-terminal signal sequence for membrane targeting. Proteins from this family have been shown to play vital roles, such as in membrane trafficking and apoptosis, in eukaryotes; however, their role in prokaryotes is largely unexplored. Here, we found that the transcription of elaB is induced in the stationary phase in E. coli and stationary-phase sigma factor RpoS regulates elaB transcription by binding to the promoter of elaB. Moreover, ElaB protects cells against oxidative stress and heat shock stress. However, unlike membrane peptide toxins TisB and GhoT, ElaB does not lead to cell death, and the deletion of elaB greatly increases persister cell formation. Therefore, we demonstrate that disruption of C-tail-anchored inner membrane proteins can reduce stress resistance; it can also lead to deleterious effects, such as increased persistence, in E. coli. IMPORTANCE Escherichia coli synthesizes dozens of poorly understood small membrane proteins containing a predicted transmembrane domain. In this study, we characterized the function of the C-tail-anchored inner membrane protein ElaB in E. coli. ElaB increases resistance to oxidative stress and heat stress, while inactivation of ElaB leads to high persister cell formation. We also demonstrated that the transcription of elaB is under the direct regulation of stationary-phase sigma factor RpoS. Thus, our study reveals that small inner membrane proteins may have important cellular roles during the stress response.

scholarly journals A nascent membrane protein is located adjacent to ER membrane proteins throughout its integration and translation.

1991 ◽  
Vol 112 (5) ◽  
pp. 809-821 ◽  
Author(s):  
R N Thrift ◽  
D W Andrews ◽  
P Walter ◽  
A E Johnson
Keyword(s):  
Membrane Proteins ◽  
Membrane Protein ◽  
Transmembrane Domain ◽  
Signal Sequence ◽  
Secretory Protein ◽  
In Vitro Translation ◽  
Nascent Chain ◽  
Transmembrane Sequence ◽  
Er Membrane

The immediate environment of nascent membrane proteins undergoing integration into the ER membrane was investigated by photocrosslinking. Nascent polypeptides of different lengths, each containing a single IgM transmembrane sequence that functions either as a stop-transfer or a signal-anchor sequence, were synthesized by in vitro translation of truncated mRNAs in the presence of N epsilon-(5-azido-2-nitrobenzoyl)-Lys-tRNA, signal recognition particle, and microsomal membranes. This yielded nascent chains with photoreactive probes at one end of the transmembrane sequence where two lysine residues are located. When irradiated, these nascent chains reacted covalently with several ER proteins. One prominent crosslinking target was a glycoprotein similar in size to a protein termed mp39, shown previously to be situated adjacent to a secretory protein during its translocation across the ER membrane (Krieg, U. C., A. E. Johnson, and P. Walter. 1989. J. Cell Biol. 109:2033-2043; Wiedmann, M., D. Goerlich, E. Hartmann, T. V. Kurzchalia, and T. A. Rapoport. 1989. FEBS (Fed. Eur. Biochem. Soc.) Lett. 257:263-268) and likely to be identical to a protein previously designated the signal sequence receptor (Wiedmann, M., T. V. Kurzchalia, E. Hartmann, and T. A. Rapoport. 1987. Nature (Lond.). 328:830-833). Changing the orientation of the transmembrane domain in the bilayer, or making the transmembrane domain the first topogenic sequence in the nascent chain instead of the second, did not significantly alter the identities of the ER proteins that were the primary crosslinking targets. Furthermore, the nascent chains crosslinked to the mp39-like glycoprotein and other microsomal proteins even after the cytoplasmic tail of the nascent chain had been lengthened by nearly 100 amino acids beyond the stop-transfer sequence. Yet when the nascent chain was allowed to terminate normally, the major photocrosslinks were no longer observed, including in particular that to the mp39-like glycoprotein. These results show that the transmembrane segment of a nascent membrane protein is located adjacent to the mp39-like glycoprotein and other ER proteins during the integration process, and that at least a portion of the nascent chain remains in close proximity to these ER proteins until translation has been completed.

scholarly journals TMEM120A is a coenzyme A-binding membrane protein with structural similarities to ELOVL fatty acid elongase

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Jing Xue ◽  
Yan Han ◽  
Hamid Baniasadi ◽  
Weizhong Zeng ◽  
Jimin Pei ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Membrane Protein ◽  
Coenzyme A ◽  
Transmembrane Domain ◽  
Coiled Coil ◽  
Structural Features ◽  
Mechanosensitive Channel ◽  
Transmembrane Helices ◽  
Long Chain Fatty Acid ◽  
Fatty Acid Elongase

TMEM120A, also named as TACAN, is a novel membrane protein highly conserved in vertebrates and was recently proposed to be a mechanosensitive channel involved in sensing mechanical pain. Here we present the single particle cryo-EM structure of human TMEM120A which forms a tightly packed dimer with extensive interactions mediate by the N-terminal coiled coil domain (CCD), the C-terminal transmembrane domain (TMD), and the re-entrant loop between the two domains. The TMD of each TMEM120A subunit contains six transmembrane helices (TMs) and has no clear structural feature of a channel protein. Instead, the six TMs form an α-barrel with a deep pocket where a coenzyme A (CoA) molecule is bound. Intriguingly, some structural features of TMEM120A resemble those of elongase for very long-chain fatty acid (ELOVL) despite low sequence homology between them, pointing to the possibility that TMEM120A may function as an enzyme for fatty acid metabolism, rather than a mechanosensitive channel.

Mechanisms underlying drug-mediated regulation of membrane protein function

2021 ◽  
Vol 118 (46) ◽  
pp. e2113229118
Author(s):  
Radda Rusinova ◽  
Changhao He ◽  
Olaf S. Andersen
Keyword(s):  
Membrane Proteins ◽  
Membrane Protein ◽  
Lipid Bilayer ◽  
Conformational Changes ◽  
Protein Function ◽  
Nonspecific Binding ◽  
Drug Induced ◽  
Protein Conformational Changes ◽  
Potassium Channel Kcsa ◽  
Membrane Protein Function

The hydrophobic coupling between membrane proteins and their host lipid bilayer provides a mechanism by which bilayer-modifying drugs may alter protein function. Drug regulation of membrane protein function thus may be mediated by both direct interactions with the protein and drug-induced alterations of bilayer properties, in which the latter will alter the energetics of protein conformational changes. To tease apart these mechanisms, we examine how the prototypical, proton-gated bacterial potassium channel KcsA is regulated by bilayer-modifying drugs using a fluorescence-based approach to quantify changes in both KcsA function and lipid bilayer properties (using gramicidin channels as probes). All tested drugs inhibited KcsA activity, and the changes in the different gating steps varied with bilayer thickness, suggesting a coupling to the bilayer. Examining the correlations between changes in KcsA gating steps and bilayer properties reveals that drug-induced regulation of membrane protein function indeed involves bilayer-mediated mechanisms. Both direct, either specific or nonspecific, binding and bilayer-mediated mechanisms therefore are likely to be important whenever there is overlap between the concentration ranges at which a drug alters membrane protein function and bilayer properties. Because changes in bilayer properties will impact many diverse membrane proteins, they may cause indiscriminate changes in protein function.

scholarly journals Changes in membrane proteins associated with inhibition of the general amino acid permease of yeast (Saccharomyces cerevisiae)

1981 ◽  
Vol 196 (2) ◽  
pp. 531-536 ◽  
Author(s):  
J R Woodward ◽  
H L Kornberg
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Amino Acids ◽  
Amino Acid ◽  
Membrane Proteins ◽  
Membrane Protein ◽  
Wild Type ◽  
Amino Acid Permease ◽  
Yeast Saccharomyces Cerevisiae ◽  
General Amino Acid Permease ◽  
Wild Type Yeast

The general amino acid permease (‘Gap’) system of the wild-type yeast (Saccharomyces cerevisiae) strain Y185 is inhibited by the uptake and accumulation of its substrate amino acids. Surprisingly, this inhibition persists even after ‘pools’ of amino acids, accumulated initially, have returned to normal sizes. Recovery from this inhibition depends on a supply of energy and involves the synthesis of a membrane protein component of the Gap system.

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