Colicins exploit native disorder to gain cell entry: a hitchhiker's guide to translocation

2008 ◽  
Vol 36 (6) ◽  
pp. 1409-1413 ◽  
Author(s):  
Daniel A. Bonsor ◽  
Nicola A. Meenan ◽  
Colin Kleanthous
Keyword(s):  
Protein Interactions ◽  
Nuclease Activity ◽  
Supramolecular Complex ◽  
Membrane Receptors ◽  
Cell Entry ◽  
Periplasmic Protein ◽  
Protein Protein Interactions ◽  
Protein Toxins ◽  
A Cell ◽  
Colicin E9

The translocation of protein toxins into a cell relies on a myriad of protein–protein interactions. One such group of toxins are enzymatic E colicins, protein antibiotics produced by Escherichia coli in times of stress. These proteins subvert ordinary nutrient uptake mechanisms to enter the cell and unleash nuclease activity. We, and others, have previously shown that uptake of ColE9 (colicin E9) is dependent on engagement of the OM (outer membrane) receptors BtuB and OmpF as well as recruitment of the periplasmic protein TolB, forming a large supramolecular complex. Intriguingly, colicins bind TolB using a natively disordered region to mimic the interaction of TolB with Pal (peptidoglycan-associated lipoprotein). This is thought to trigger OM instability and prime the system for translocation. Here, we review key interactions in the assembly of this ‘colicin translocon’ and discuss the key role disorder plays in achieving uptake.

Proteomic Characterization of Protein-Protein Interactions

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Veenstra TD ◽  
Keyword(s):  
Protein Interactions ◽  
Disease Diagnosis ◽  
Cell System ◽  
Protein Protein Interactions ◽  
Novel Technologies ◽  
Cell Functions ◽  
Single Protein ◽  
A Cell ◽  
Molecular Components

Identifying all the molecular components within a living cell is the first step into understanding how it functions. To further understand how a cell functions requires identifying the interactions that occur between these components. This fact is especially relevant for proteins. No protein within a human cell functions on its own without interacting with another biomolecule - usually another protein. While Protein-Protein Interactions (PPI) have historically been determined by examining a single protein per study, novel technologies developed over the past couple of decades are enabling high-throughput methods that aim to describe entire protein networks within cells. In this review, some of the technologies that have led to these developments are described along with applications of these techniques. Ultimately the goal of these technologies is to map out the entire circuitry of PPI within human cells to be able to predict the global consequences of perturbations to the cell system. This predictive capability will have major impacts on the future of both disease diagnosis and treatment.

scholarly journals Mitochondria: Regulators of Cell Death and Survival

2002 ◽  
Vol 2 ◽  
pp. 1569-1578 ◽  
Author(s):  
David J. Granville ◽  
Roberta A. Gottlieb
Keyword(s):  
Cell Death ◽  
Conformational Changes ◽  
Protein Interactions ◽  
Apoptotic Cell ◽  
Critical Role ◽  
Death Process ◽  
Protein Protein Interactions ◽  
Ionic Changes ◽  
A Cell ◽  
Cyt C

The past 5 years has seen an intense surge in research devoted toward understanding the critical role of mitochondria in the regulation of cell death. Apoptosis can be initiated by a wide array of stimuli, inducing multiple signaling pathways that, for the most part, converge at the mitochondrion. Although classically considered the powerhouses of the cell, it is now understood that mitochondria are also “gatekeepers” that ultimately determine the fate of the cell. The mitochondrial decision as to whether a cell lives or dies is complex, involving protein-protein interactions, ionic changes, reactive oxygen species, and other mechanisms that require further elucidation. Once the death process is initiated, mitochondria undergo conformational changes, resulting in the release of cytochrome c (cyt c), caspases, endonucleases, and other factors leading to the onset and execution of apoptosis. The present review attempts to outline the complex milieu of events regulating the mitochondrial commitment to and processes involved in the implementation of the executioner phase of apoptotic cell death.

scholarly journals A cell-penetrant lactam-stapled peptide for targeting eIF4E protein-protein interactions

2020 ◽  
Vol 205 ◽  
pp. 112655
Author(s):  
Erin E. Gallagher ◽  
Arya Menon ◽  
Alyah F. Chmiel ◽  
Kirsten Deprey ◽  
Joshua A. Kritzer ◽  
...  
Keyword(s):  
Protein Interactions ◽  
Protein Protein Interactions ◽  
Stapled Peptide ◽  
A Cell

scholarly journals Protein–protein interactions in intracellular Ca2+-release channel function

1999 ◽  
Vol 337 (3) ◽  
pp. 345-361 ◽  
Author(s):  
John J. MACKRILL
Keyword(s):  
Protein Interactions ◽  
Ryanodine Receptors ◽  
Accessory Proteins ◽  
Protein Protein Interactions ◽  
Release Channel ◽  
Specific Effects ◽  
Complex Protein ◽  
A Cell ◽  
And Function ◽  
Opposing Effects

Release of Ca2+ ions from intracellular stores can occur via two classes of Ca2+-release channel (CRC) protein, the inositol 1,4,5-trisphosphate receptors (InsP3Rs) and the ryanodine receptors (RyRs). Multiple isoforms and subtypes of each CRC class display distinct but overlapping distributions within mammalian tissues. InsP3Rs and RyRs interact with a plethora of accessory proteins which modulate the activity of their intrinsic channels. Although many aspects of CRC structure and function have been reviewed in recent years, the properties of proteins with which they interact has not been comprehensively surveyed, despite extensive current research on the roles of these modulators. The aim of this article is to review the regulation of CRC activity by accessory proteins and, wherever possible, to outline the structural details of such interactions. The CRCs are large transmembrane proteins, with the bulk of their structure located cytoplasmically. Intra- and inter-complex protein–protein interactions between these cytoplasmic domains also regulate CRC function. Some accessory proteins modulate channel activity of all CRC subtypes characterized, whereas other have class- or even isoform-specific effects. Certain accessory proteins exert both direct and indirect forms of regulation on CRCs, occasionally with opposing effects. Others are themselves modulated by changes in Ca2+ concentration, thereby participating in feedback mechanisms acting on InsP3R and RyR activity. CRCs are therefore capable of integrating numerous signalling events within a cell by virtue of such protein–protein interactions. Consequently, the functional properties of InsP3Rs and RyRs within particular cells and subcellular domains are ‘customized ’ by the accessory proteins present.

scholarly journals A protein tertiary structure mimetic modulator of the Hippo signalling pathway

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Hélène Adihou ◽  
Ranganath Gopalakrishnan ◽  
Tim Förster ◽  
Stéphanie M. Guéret ◽  
Raphael Gasper ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Protein Interactions ◽  
Tertiary Structure ◽  
Hippo Pathway ◽  
Signalling Pathway ◽  
Protein Protein Interactions ◽  
Protein Tertiary Structure ◽  
A Cell ◽  
Chemical Modulation ◽  
Hippo Signalling

Abstract Transcription factors are key protein effectors in the regulation of gene transcription, and in many cases their activity is regulated via a complex network of protein–protein interactions (PPI). The chemical modulation of transcription factor activity is a long-standing goal in drug discovery but hampered by the difficulties associated with the targeting of PPIs, in particular when extended and flat protein interfaces are involved. Peptidomimetics have been applied to inhibit PPIs, however with variable success, as for certain interfaces the mimicry of a single secondary structure element is insufficient to obtain high binding affinities. Here, we describe the design and characterization of a stabilized protein tertiary structure that acts as an inhibitor of the interaction between the transcription factor TEAD and its co-repressor VGL4, both playing a central role in the Hippo signalling pathway. Modification of the inhibitor with a cell-penetrating entity yielded a cell-permeable proteomimetic that activates cell proliferation via regulation of the Hippo pathway, highlighting the potential of protein tertiary structure mimetics as an emerging class of PPI modulators.

NPXY motifs control the recruitment of the alpha5beta1 integrin in focal adhesions independently of the association of talin with the beta1 chain

1997 ◽  
Vol 110 (12) ◽  
pp. 1421-1430 ◽  
Author(s):  
L. Vignoud ◽  
C. Albiges-Rizo ◽  
P. Frachet ◽  
M.R. Block
Keyword(s):  
Amino Acids ◽  
Protein Interactions ◽  
Focal Adhesions ◽  
Cytoplasmic Tail ◽  
Cytoplasmic Domain ◽  
Membrane Receptors ◽  
Sufficient Information ◽  
Protein Protein Interactions ◽  
Exact Function ◽  
Beta1 Subunit

With the exception of the divergent beta4 and beta8 chains, the integrin beta subunit cytoplasmic domains are short and highly conserved sequences. Consensus motifs are found among the different cytoplasmic beta chains. Experiments using chimeric receptors demonstrated that the 47 amino acids of the beta1 subunit cytoplasmic domain contain sufficient information to target integrins to adhesion plaques. Three clusters of amino acids, named cyto-1, cyto-2 and cyto-3, seem to contribute to this localization. Cyto-2 and cyto-3 exhibit NPXY motifs. At present, the exact function of these motifs remains unknown but it is likely that these sequences are involved in protein-protein interactions. Although NPXY motifs often act as internalization signals at the cytoplasmic tail of membrane receptors, our previous results showed that the two NPXY motifs are not responsible for the alpha5beta1 integrin endocytosis. Herein, we address the question of the role of the two highly conserved NPXY motifs found in the beta1 cytoplasmic domain, and which correspond to the conserved domains cyto-2 and cyto-3. We demonstrate that, within the integrin beta1 cytoplasmic tail, the two NPXY motifs are required for the recruitment of the integrin in focal adhesions. In addition, our results indicate that these two motifs control but do not belong to the talin-binding sites. Finally, the analysis of the phenotypes of NPXY mutants reveals that the interaction of talin with the beta1 cytosolic domain is not sufficient to target the integrins to focal adhesions.

scholarly journals Thanatin targets the intermembrane protein complex required for lipopolysaccharide transport inEscherichia coli

2018 ◽  
Vol 4 (11) ◽  
pp. eaau2634 ◽  
Author(s):  
Stefan U. Vetterli ◽  
Katja Zerbe ◽  
Maik Müller ◽  
Matthias Urfer ◽  
Milon Mondal ◽  
...  
Keyword(s):  
Protein Interactions ◽  
Macromolecular Complex ◽  
Gram Negative Bacteria ◽  
Periplasmic Protein ◽  
Protein Protein Interactions ◽  
Inner Membrane ◽  
Gram Negative ◽  
Research Priority ◽  
Naturally Occurring ◽  
Bacterial Outer Membrane

With the increasing resistance of many Gram-negative bacteria to existing classes of antibiotics, identifying new paradigms in antimicrobial discovery is an important research priority. Of special interest are the proteins required for the biogenesis of the asymmetric Gram-negative bacterial outer membrane (OM). Seven Lpt proteins (LptA to LptG) associate in most Gram-negative bacteria to form a macromolecular complex spanning the entire envelope, which transports lipopolysaccharide (LPS) molecules from their site of assembly at the inner membrane to the cell surface, powered by adenosine 5′-triphosphate hydrolysis in the cytoplasm. The periplasmic protein LptA comprises the protein bridge across the periplasm, which connects LptB2FGC at the inner membrane to LptD/E anchored in the OM. We show here that the naturally occurring, insect-derived antimicrobial peptide thanatin targets LptA and LptD in the network of periplasmic protein-protein interactions required to assemble the Lpt complex, leading to the inhibition of LPS transport and OM biogenesis inEscherichia coli.

scholarly journals The metabolite α-KG induces GSDMC-dependent pyroptosis through death receptor 6-activated caspase-8

Cell Research ◽  
2021 ◽  
Author(s):  
Jia-yuan Zhang ◽  
Bo Zhou ◽  
Ru-yue Sun ◽  
Yuan-li Ai ◽  
Kang Cheng ◽  
...  
Keyword(s):  
Protein Interactions ◽  
Tumor Therapy ◽  
Death Receptor ◽  
Caspase 8 ◽  
Acidic Environment ◽  
Protein Protein Interactions ◽  
Regulated Cell Death ◽  
A Cell ◽  
Tumor Growth And Metastasis ◽  
Death Receptor 6

AbstractPyroptosis is a form of regulated cell death mediated by gasdermin family members, among which the function of GSDMC has not been clearly described. Herein, we demonstrate that the metabolite α-ketoglutarate (α-KG) induces pyroptosis through caspase-8-mediated cleavage of GSDMC. Treatment with DM-αKG, a cell-permeable derivative of α-KG, elevates ROS levels, which leads to oxidation of the plasma membrane-localized death receptor DR6. Oxidation of DR6 triggers its endocytosis, and then recruits both pro-caspase-8 and GSDMC to a DR6 receptosome through protein-protein interactions. The DR6 receptosome herein provides a platform for the cleavage of GSDMC by active caspase-8, thereby leading to pyroptosis. Moreover, this α-KG-induced pyroptosis could inhibit tumor growth and metastasis in mouse models. Interestingly, the efficiency of α-KG in inducing pyroptosis relies on an acidic environment in which α-KG is reduced by MDH1 and converted to L-2HG that further boosts ROS levels. Treatment with lactic acid, the end product of glycolysis, builds an improved acidic environment to facilitate more production of L-2HG, which makes the originally pyroptosis-resistant cancer cells more susceptible to α-KG-induced pyroptosis. This study not only illustrates a pyroptotic pathway linked with metabolites but also identifies an unreported principal axis extending from ROS-initiated DR6 endocytosis to caspase-8-mediated cleavage of GSDMC for potential clinical application in tumor therapy.

scholarly journals A cell-based screening method using an intracellular antibody for discovering small molecules targeting the translocation protein LMO2

2021 ◽  
Vol 7 (15) ◽  
pp. eabg1950
Author(s):  
Nicolas Bery ◽  
Carole J.R. Bataille ◽  
Angela Russell ◽  
Angela Hayes ◽  
Florence Raynaud ◽  
...  
Keyword(s):  
Small Molecules ◽  
Protein Interactions ◽  
Binding Sites ◽  
Screening Method ◽  
Chromosomal Translocation ◽  
Resonance Method ◽  
Protein Protein Interactions ◽  
Intracellular Antibody ◽  
A Cell

Intracellular antibodies are tools that can be used directly for target validation by interfering with properties like protein-protein interactions. An alternative use of intracellular antibodies in drug discovery is developing small-molecule surrogates using antibody-derived (Abd) technology. We previously used this strategy with an in vitro competitive surface plasmon resonance method that relied on high-affinity antibody fragments to obtain RAS-binding compounds. We now describe a novel implementation of the Abd method with a cell-based intracellular antibody–guided screening method that we have applied to the chromosomal translocation protein LMO2. We have identified a chemical series of anti-LMO2 Abd compounds that bind at the same LMO2 location as the inhibitory anti-LMO2 intracellular antibody combining site. Intracellular antibodies could therefore be used in cell-based screens to identify chemical surrogates of their binding sites and potentially be applied to any challenging proteins, such as transcription factors that have been considered undruggable.

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