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Protein unfolding and translocation

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https://www.readbyqxmd.com/read/29433415/mechanical-protein-unfolding-and-degradation
#1
Adrian O Olivares, Tania A Baker, Robert T Sauer
AAA+ proteolytic machines use energy from ATP hydrolysis to degrade damaged, misfolded, or unneeded proteins. Protein degradation occurs within a barrel-shaped self-compartmentalized peptidase. Before protein substrates can enter this peptidase, they must be unfolded and then translocated through the axial pore of an AAA+ ring hexamer. An unstructured region of the protein substrate is initially engaged in the axial pore, and conformational changes in the ring, powered by ATP hydrolysis, generate a mechanical force that pulls on and denatures the substrate...
February 10, 2018: Annual Review of Physiology
https://www.readbyqxmd.com/read/29423676/heat-shock-transcriptional-factor-mediates-mitochondrial-unfolded-protein-response
#2
Naoki Koike, Yuuki Hatano, Takashi Ushimaru
For maintenance of cytoplasmic protein quality control (PQC), cytoplasmic heat shock proteins (HSPs) negatively control heat shock transcriptional factor (HSF) in a negative feedback loop. However, how mitochondrial protein quality control (mtPQC) is maintained is largely unknown. Here we present evidence that HSF directly monitors mtPQC in the budding yeast Saccharomyces cerevisiae. Mitochondrial HSP70 (Ssc1) negatively regulated HSF activity. Importantly, HSF was localized not only in the nucleus but also on mitochondria...
February 8, 2018: Current Genetics
https://www.readbyqxmd.com/read/29393572/tetracycline-alters-gene-expression-in-salmonella-strains-that-harbor-the-tn10-transposon
#3
M Hüttener, A Prieto, S Aznar, M Dietrich, S Paytubi, A Juárez
In this report we show that bacterial plasmids that harbor the Tn10 transposon (i.e., the IncHI1 plasmid R27) modify expression of different Salmonella regulons responding to the presence of tetracycline (Tc) in the medium. By using as a model the Tc-dependent upregulation of the ibpAB operon (which belongs to the heat shock regulon), we have identified Tn10- tetA (coding for a Tc efflux pump) and adjacent tetC sequences as required for ibpAB upregulation. Characterization of transcripts in the tetAC region showed that tetA transcription can continue into tetC sequences, generating a long 3'UTR sequence, which can protect transcripts from RNA processing, thus increasing expression of TetA protein...
February 2, 2018: Environmental Microbiology Reports
https://www.readbyqxmd.com/read/29369790/homeostatic-interplay-between-foxo-protein-and-er-proteostasis-in-cancer-and-other-diseases
#4
REVIEW
Matías González-Quiroz, Hery Urra, Celia María Limia, Claudio Hetz
Cancer cells are exposed to several adverse conditions within the tumor microenvironment that challenge cells to adapt and survive. Several of these homeostatic perturbations insults alter the normal function of the endoplasmic reticulum (ER), resulting in the accumulation of misfolded proteins. ER stress triggers a conserved signaling pathway known as the unfolded protein response (UPR) to cope with the stress or trigger apoptosis of damaged cells. The UPR has been described as a major driver of the acquisition of malignant characteristics that ultimately lead to tumor progression...
January 21, 2018: Seminars in Cancer Biology
https://www.readbyqxmd.com/read/29317503/er-stress-mobilization-of-death-associated-protein-kinase-1-dependent-xenophagy-counteracts-mitochondria-stress-induced-epithelial-barrier-dysfunction
#5
Fernando Lopes, Åsa V Keita, Alpana Saxena, Jose Luis Reyes, Nicole Mancini, Ala Al Rajabi, Arthur Wang, Cristiane Baggio, Michael Dicay, Rob van Dalen, Younghee Ahn, Matheus Carneiro, Nathan Peters, Jong M Rho, Wallace MacNaughton, Stephan E Girardin, Humberto Jijon, Dana J Philpott, Johan D Söderholm, Derek M McKay
The gut microbiome contributes to inflammatory bowel disease (IBD), in which bacteria can be present within the epithelium. Epithelial barrier function is decreased in IBD, and dysfunctional epithelial mitochondria and endoplasmic reticulum (ER) stress have been individually associated with IBD. We therefore hypothesized that the combination of ER and mitochondrial stresses significantly disrupt epithelial barrier function. Here, we treated human colonic biopsies, epithelial colonoids, and epithelial cells with an uncoupler of oxidative phosphorylation, dinitrophenol (DNP), with or without the ER stressor tunicamycin, and assessed epithelial barrier function by monitoring internalization and translocation of commensal bacteria...
January 9, 2018: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/29311273/translocation-through-the-conjugative-type-4-secretion-system-requires-unfolding-of-its-protein-substrate
#6
Martina Trokter, Gabriel Waksman
Bacterial conjugation, a mechanism of horizontal gene transfer, is the major means by which antibiotic resistance spreads among bacteria (1, 2). Conjugative plasmids are transferred from one bacterium to another through a type IV secretion system (T4SS) in a form of single-stranded DNA covalently attached to a protein called relaxase. The relaxase is fully functional both in a donor cell (prior to conjugation) and recipient cell (after conjugation). Here we demonstrate that the protein substrate has to unfold for efficient translocation through the conjugative T4SS...
January 8, 2018: Journal of Bacteriology
https://www.readbyqxmd.com/read/29208936/disulfide-driven-folding-for-a-conditionally-disordered-protein
#7
Hugo Fraga, Jordi Pujols, Marcos Gil-Garcia, Alicia Roque, Ganeko Bernardo-Seisdedos, Carlo Santambrogio, Joan-Josep Bech-Serra, Francesc Canals, Pau Bernadó, Rita Grandori, Oscar Millet, Salvador Ventura
Conditionally disordered proteins are either ordered or disordered depending on the environmental context. The substrates of the mitochondrial intermembrane space (IMS) oxidoreductase Mia40 are synthesized on cytosolic ribosomes and diffuse as intrinsically disordered proteins to the IMS, where they fold into their functional conformations; behaving thus as conditionally disordered proteins. It is not clear how the sequences of these polypeptides encode at the same time for their ability to adopt a folded structure and to remain unfolded...
December 5, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29180014/structural-insights-into-the-oligomerization-of-ftsh-periplasmic-domain-from-thermotoga-maritima
#8
Jun Yop An, Humayun Sharif, Gil Bu Kang, Kyung Jin Park, Jung-Gyu Lee, Sukyeong Lee, Mi Sun Jin, Ji-Joon Song, Jimin Wang, Soo Hyun Eom
Prompt removal of misfolded membrane proteins and misassembled membrane protein complexes is essential for membrane homeostasis. However, the elimination of these toxic proteins from the hydrophobic membrane environment has high energetic barriers. The transmembrane protein, FtsH, is the only known ATP-dependent protease responsible for this task. The mechanisms by which FtsH recognizes, unfolds, translocates, and proteolyzes its substrates remain unclear. The structure and function of the ATPase and protease domains of FtsH have been previously characterized while the role of the FtsH periplasmic domain has not clearly identified...
November 24, 2017: Biochemical and Biophysical Research Communications
https://www.readbyqxmd.com/read/29175998/structural-determinants-for-protein-unfolding-and-translocation-by-the-hsp104-protein-disaggregase
#9
Jungsoon Lee, Nuri Sung, Lythou Yeo, Changsoo Chang, Sukyeong Lee, Francis T F Tsai
The ring-forming Hsp104 ATPase cooperates with Hsp70 and Hsp40 molecular chaperones to rescue stress-damaged proteins from both amorphous and amyloid-forming aggregates. The ability to do so relies upon pore loops present in the ATP-binding domains of Hsp104 (loop-1 and loop-2 in AAA-1, and loop-3 in AAA-2), which face the protein translocating channel and couple ATP-driven changes in pore loop conformation to substrate translocation. A hallmark of loop-1 and loop-3 is an invariable and mutational sensitive aromatic amino acid (Tyr257 and Tyr662) involved in substrate binding...
November 24, 2017: Bioscience Reports
https://www.readbyqxmd.com/read/29152155/chibby-1-a-new-component-of-%C3%AE-catenin-signaling-in-chronic-myeloid-leukemia
#10
REVIEW
Manuela Mancini, Simona Soverini, Gabriele Gugliotta, Maria Alessandra Santucci, Gianantonio Rosti, Michele Cavo, Giovanni Martinelli, Fausto Castagnetti
Chibby 1 (CBY1) is a small and evolutionarily conserved protein, which act as β-catenin antagonist. CBY1 is encoded by C22orf2 (22q13.1) Its antagonistic function on β-catenin involves the direct interaction with: The C-terminal activation domain of β-catenin, which hinders β-catenin binding with Tcf/Lef transcription factors hence repressing β-catenin transcriptional activation. 14-3-3 scaffolding proteins (σ or ξ), which drive CBY1 nuclear export into a stable tripartite complex with β-catenin. The relative proximity of C22orf2 gene encoding for CBY1 to the BCR breakpoint on chromosome 22q11, whose translocation and rearrangement with the c-ABL is the causative event of chronic myeloid leukemia (CML), suggested that gene haploinsufficiency may play a role in the disease pathogenesis and progression...
October 20, 2017: Oncotarget
https://www.readbyqxmd.com/read/29145399/point-mutation-in-d8c-domain-of-tamm-horsfall-protein-uromodulin-in-transgenic-mice-causes-progressive-renal-damage-and-hyperuricemia
#11
Lijie Ma, Yan Liu, Nichole K Landry, Tarek M El-Achkar, John C Lieske, Xue-Ru Wu
Hereditary mutations in Tamm-Horsfall protein (THP/uromodulin) gene cause autosomal dominant kidney diseases characterized by juvenile-onset hyperuricemia, gout and progressive kidney failure, although the disease pathogenesis remains unclear. Here we show that targeted expression in transgenic mice of a mutation within the domain of 8 cysteines of THP in kidneys' thick ascending limb (TAL) caused unfolded protein response in younger (1-month old) mice and apoptosis in older (12-month old) mice. While the young mice had urine concentration defects and polyuria, such defects progressively reversed in the older mice to marked oliguria, highly concentrated urine, fibrotic kidneys and reduced creatinine clearance...
2017: PloS One
https://www.readbyqxmd.com/read/29129755/phylogenetic-analysis-predicts-structural-divergence-for-proteobacterial-clpc-proteins
#12
Justin M Miller, Hamza Chaudhary, Justin D Marsee
Regulated proteolysis is required in all organisms for the removal of misfolded or degradation-tagged protein substrates in cellular quality control pathways. The molecular machines that catalyze this process are known as ATP-dependent proteases with examples that include ClpAP and ClpCP. Clp/Hsp100 subunits form ring-structures that couple the energy of ATP binding and hydrolysis to protein unfolding and subsequent translocation of denatured protein into the compartmentalized ClpP protease for degradation...
November 9, 2017: Journal of Structural Biology
https://www.readbyqxmd.com/read/29111118/hsp90-and-thioredoxin-thioredoxin-reductase-enable-the-catalytic-activity-of-clostridial-neurotoxins-inside-nerve-terminals
#13
Marco Pirazzini, Domenico Azarnia Tehran, Giulia Zanetti, Ornella Rossetto, Cesare Montecucco
Botulinum (BoNTs) and tetanus (TeNT) neurotoxins are the most toxic substances known and form the growing family of Clostridial neurotoxins (CNT), the etiologic agents of botulism and tetanus. CNT are composed of a metalloprotease light chain (L), linked via a disulfide bond to a heavy chain (H). H mediates the binding to nerve terminals and the membrane translocation of L into the cytosol, where its substrates, the three SNARE proteins, are localized. L translocation is accompanied by unfolding and, once delivered on the cytosolic side of the endosome membrane, it has to be reduced and reacquire the native fold to be active...
October 27, 2017: Toxicon: Official Journal of the International Society on Toxinology
https://www.readbyqxmd.com/read/29078392/exploitation-of-an-iron-transporter-for-bacterial-protein-antibiotic-import
#14
Paul White, Amar Joshi, Patrice Rassam, Nicholas G Housden, Renata Kaminska, Jonathan D Goult, Christina Redfield, Laura C McCaughey, Daniel Walker, Shabaz Mohammed, Colin Kleanthous
Unlike their descendants, mitochondria and plastids, bacteria do not have dedicated protein import systems. However, paradoxically, import of protein bacteriocins, the mechanisms of which are poorly understood, underpins competition among pathogenic and commensal bacteria alike. Here, using X-ray crystallography, isothermal titration calorimetry, confocal fluorescence microscopy, and in vivo photoactivatable cross-linking of stalled translocation intermediates, we demonstrate how the iron transporter FpvAI in the opportunistic pathogen Pseudomonas aeruginosa is hijacked to translocate the bacteriocin pyocin S2 (pyoS2) across the outer membrane (OM)...
November 7, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/29054272/insights-on-the-hla-binding-peptidome-in-cancer
#15
Douglas F Lake
The intracellular compartments for proteolytic antigen processing in tumor cells produce peptides that are presented by MHC molecules to T cells. But first, the ubiquitin ligase system tags defective, misfolded, aged, and unstable proteins for degradation through the proteasome. Ubiqitinated proteins are unfolded and fed into the barrel-shaped core of the proteasome where a collection of multiple different proteases cleave proteins into oligopeptides. After exiting the proteasome, these oligopeptides are either completely degraded into amino acids or trimmed at the N- and C-termini so that they bind to transporter associated with antigen processing (TAP)...
2017: Enzymes
https://www.readbyqxmd.com/read/29030433/dysregulation-of-the-mitochondrial-unfolded-protein-response-induces-non-apoptotic-dopaminergic-neurodegeneration-in-c-elegans-models-of-parkinson-s-disease
#16
Bryan A Martinez, Daniel A Petersen, Anthony L Gaeta, Samuel P Stanley, Guy A Caldwell, Kim A Caldwell
Due to environmental insult or innate genetic deficiency, protein folding environments of the mitochondrial matrix are prone to dysregulation, prompting the activation of a specific organellar stress-response mechanism, the mitochondrial unfolded protein response (UPR(MT)). In Caenorhabditis elegans, mitochondrial damage leads to nuclear translocation of the ATFS-1 transcription factor to activate the UPR(MT) After short-term acute stress has been mitigated, the UPR(MT) is eventually suppressed to restore homeostasis to C...
November 15, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28988953/meddling-with-fate-the-proteasomal-deubiquitinating-enzymes
#17
REVIEW
Stefanie A H de Poot, Geng Tian, Daniel Finley
Three deubiquitinating enzymes-Rpn11, Usp14, and Uch37-are associated with the proteasome regulatory particle. These enzymes allow proteasomes to remove ubiquitin from substrates before they are translocated into the core particle to be degraded. Although the translocation channel is too narrow for folded proteins, the force of translocation unfolds them mechanically. As translocation proceeds, ubiquitin chains bound to substrate are drawn to the channel's entry port, where they can impede further translocation...
November 10, 2017: Journal of Molecular Biology
https://www.readbyqxmd.com/read/28980803/analysis-of-pore-formation-and-protein-translocation-using-large-biological-nanopores
#18
Hirokazu Watanabe, Alberto Gubbiotti, Mauro Chinappi, Natsumi Takai, Koji Tanaka, Kouhei Tsumoto, Ryuji Kawano
This paper describes the analysis of pore formation and detection of a single protein molecule using a large nanopore among five different pore-forming proteins. We demonstrate that the identification of appropriate pores for nanopore sensing can be achieved by classifying the channel current signals and performing noise analysis. Through these analyses, we selected a perforin nanopore from the membrane attack complex/perforin superfamily and attempted to use it to detect the granzyme B protein, a serine protease...
November 7, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28978049/ros-independent-nrf2-activation-in-prostate-cancer
#19
Ilaria Bellezza, Paolo Scarpelli, Salvatore V Pizzo, Silvia Grottelli, Egidia Costanzi, Alba Minelli
In prostate cancer, oxidative stress and the subsequent Nrf2 activation promote the survival of cancer cells and acquired chemoresistance. Nrf2 links prostate cancer to endoplasmic reticulum stress, an event that triggers the unfolded protein response, aiming to restore cellular homeostasis as well as an adaptive survival mechanism. Glucose-regulated protein of 78 kD /immunoglobulin heavy chain binding protein (GRP78/BiP) is a key molecular chaperone in the endoplasmic reticulum that, when expressed at the cell surface, acts as a receptor for several signaling pathways enhancing antiapoptotic and proliferative signals...
September 15, 2017: Oncotarget
https://www.readbyqxmd.com/read/28920507/navigating-the-structure-function-evolutionary-relationship-of-csaa-chaperone-in-archaea
#20
Archana Sharma, Shikha Rani, Manisha Goel
CsaA is a protein involved in the post-translational translocation of proteins across the cytoplasmic membrane. It is considered to be a functional homolog of SecB which participates in the Sec-dependent translocation pathway in an analogous manner. CsaA has also been reported to act as a molecular chaperone, preventing aggregation of unfolded proteins. It is essentially a prokaryotic protein which is absent in eukaryotes, but found extensively in bacteria and earlier thought to be widely present in archaea...
September 18, 2017: Critical Reviews in Microbiology
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