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membrane protein folding

Melanie Ott, Débora Marques, Christina Funk, Susanne M Bailer
BACKGROUND: Herpes simplex virus type 1 (HSV1), a member of the alphaherpesvirinae, can cause recurrent facial lesions and encephalitis. Two membrane envelopment processes, one at the inner nuclear membrane and a second at cytoplasmic membranes are crucial for a productive viral infection. Depending on the subfamily, herpesviruses encode more than 11 different transmembrane proteins including members of the tail-anchored protein family. HSV1 encodes three tail-anchored proteins pUL34, pUL56 and pUS9 characterized by a single hydrophobic region positioned at their C-terminal end that needs to be released from the ribosome prior to posttranslational membrane insertion...
October 20, 2016: Virology Journal
Jennifer L Smith, Corey L Anderson, Don E Burgess, Claude S Elayi, Craig T January, Brian P Delisle
The molecular mechanisms underlying congenital long QT syndrome (LQTS) are now beginning to be understood. New insights into the etiology and therapeutic strategies are emerging from heterologous expression studies of LQTS-linked mutant proteins, as well as inducible pluripotent stem cell derived cardiomyocytes (iPSC-CMs) from LQTS patients. This review focuses on the major molecular mechanism that underlies LQTS type 2 (LQT2). LQT2 is caused by loss of function (LOF) mutations in KCNH2 (also known as the human Ether-à-go-go-Related Gene or hERG)...
October 2016: Journal of Arrhythmia
Nathan J Hare, Ling Y Lee, Ian Loke, Warwick J Britton, Bernadette M Saunders, Morten Thaysen-Andersen
Tuberculosis (TB) remains a prevalent and lethal infectious disease. The glycobiology associated with Mycobacterium tuberculosis infection of front-line alveolar macrophages is still unresolved. Herein, we investigated the regulation of protein N-glycosylation in human macrophages and their secreted microparticles (MPs) used for intercellular communication upon M. tb infection. LC-MS/MS-based proteomics and glycomics were performed to monitor the regulation of glycosylation enzymes and receptors and the N-glycome in in vitro-differentiated macrophages and in isolated MPs upon M...
October 19, 2016: Journal of Proteome Research
Mengmeng Wang, Amanda K Kussrow, Mireia Fernandez Ocana, Jeffrey R Chabot, Christopher S Lepsy, Darryl J Bornhop, Denise M O'Hara
BACKGROUND AND PURPOSE: A monoclonal antibody (PF-00547659) against Mucosal Adressin Cell Adhesion Molecule (MAdCAM), expressed as both soluble (sMAdCAM) and trans-membrane (mMAdCAM) target forms, showed over 30-fold difference in antibody-target KD between in vitro (Biacore) and clinically derived (KD,in-vivo ) values. Back-scattering interferometry (BSI) was applied to acquire physiologically relevant KD values which were used to establish in vitro and in vivo correlation (IVIVC). EXPERIMENTAL APPROACH: Back-scattering interferometry (BSI) was applied to obtain KD values between PF-00547659 and recombinant human MAdCAM in buffer or CHO cells and endogenous MAdCAM in human serum or colon tissue...
October 19, 2016: British Journal of Pharmacology
Fernando J Sialana, Peter Gulyassy, Peter Májek, Evelina Sjöstedt, Viktor Kis, André C Müller, Elena L Rudashevskaya, Jan Mulder, Keiryn L Bennett, Gert Lubec
The molecular composition of synaptic signal transduction machineries shapes synaptic neurotransmission. The repertoire of receptors, transporters and channels (RTCs) comprises major signaling events in the brain. RTCs are conventionally studied by candidate immunohistochemistry and biochemistry, which are low throughput with resolution greatly affected by available immunoreagents and membrane interference. Therefore, a comprehensive resource of synaptic brain RTCs is still lacking. In particular, studies on the detergent-soluble synaptosomal fraction, known to contain transporters and channels, are limited...
October 19, 2016: Proteomics
Wei Hu, Zhiqiang Ma, Shouyin Di, Shuai Jiang, Yue Li, Chongxi Fan, Yang Yang, Dongjin Wang
The endoplasmic reticulum (ER) is an important intracellular membranous organelle. Previous studies have demonstrated that the ER is responsible for protein folding and trafficking, lipid synthesis, and the maintenance of calcium homeostasis. Interestingly, the morphology and structure of the ER were recently found to be important. Melatonin is a hormone that anticipates the daily onset of darkness in mammals, and it is well known that melatonin acts as an antioxidant by scavenging free radicals and increasing the activity of antioxidant enzymes in the body...
October 19, 2016: British Journal of Pharmacology
Manish Kumar Pal, Shyama Pyari Jaiswar, Ajeet Kumar Srivastav, Shruti Goyal, Ashish Dwivedi, Ankit Verma, Jyoti Singh, Anumesh Kumar Pathak, Pushpa Lata Sankhwar, Ratan Singh Ray
Ovarian cancer is fourth most common and lethal among all gynecologic malignancies. The chemotherapy usually requires in all stages of ovarian cancer but drugs have several side effects. We hypothesized that use of combination therapy of paclitaxel (PTX) and phytochemical piperine (PIP) may reduce the PTX dose as well as toxicity.The human ovarian adenocarcinomas SKOV3 cell treated with PTX-5nM and PIP-10µM after determination of IC50 by MTT assay. Reactive oxygen species generation, mitochondrial membrane potential (MMP), DNA damage, cell death pathway markers as release of cyt-c, Bax/Bcl2-caspase-3 and cell cycle arrest were analyzed...
October 15, 2016: European Journal of Pharmacology
Maddison Turner, Larissa Reid, Mercedes Munkonda, Dylan Burger
OBJECTIVE: Diabetes and hypertension are cognate diseases that often coexist, potentiating one's risk for cardiovascular complications. Both diseases are typified by the development of endothelial dysfunction and are accompanied by increased circulating endothelial microparticles (eMPs). Microparticles are small membrane-derived vesicles that are secreted ubiquitously following cell stress. We have previously shown that eMPs are sensitive markers of vascular injury in hypertension and identified eMP-mediated signaling pathways that lead to endothelial injury...
September 2016: Journal of Hypertension
Cuiling Wu, Dan Liu, Xinghao Yang, Ribang Wu, Jiang Zhang, Jiafeng Huang, Hailun He
Pseudoalteromonas sp. CSN423, a marine strain, can express a major protease designated as E423 and it was secreted into the supernatant. To improve the protease E423 yield, Pseudoalteromonas sp. CSN423 was subjected to mutagenesis using UV irradiation. Mutant strain with 5.1-fold higher protease yield was isolated and named as Pseudoalteromonas sp. CSN423-M. Three protease bands were detected by zymography with casein as substrate, and results of mass spectrometry (MS) showed that two lower molecular weight protein bands were the same protease but with different mature forms...
October 17, 2016: Marine Biotechnology
Elsa Perrody, Laurence Abrami, Michal Feldman, Beatrice Kunz, Sylvie Urbé, Gisou van der Goot
Many membrane proteins fold inefficiently and require the help of enzymes and chaperones. Here we reveal a novel folding assistance system that operates on membrane proteins from the cytosolic side of the endoplasmic reticulum (ER). We show that folding of the Wnt signaling coreceptor LRP6 is promoted by ubiquitination of a specific lysine, retaining it in the ER while avoiding degradation. Subsequent ER exit requires removal of ubiquitin from this lysine by the deubiquitinating enzyme USP19. This ubiquitination-deubiquitination is conceptually reminiscent of the glucosylation-deglucosylation occurring in the ER lumen during the calnexin/calreticulin folding cycle...
October 18, 2016: ELife
Hye Yeon Koh, Hyun Park, Jun Hyuck Lee, Se Jong Han, Young Chang Sohn, Sung Gu Lee
Psychrobacter sp. PAMC 21119, isolated from Antarctic permafrost soil, grows and proliferates at subzero temperatures. However, its major mechanism of cold adaptation regulation remains poorly understood. We investigated the transcriptomic and proteomic responses of this species to cold temperatures by comparing profiles at -5°C and 20°C to understand how extreme microorganisms survive under subzero conditions. We found a total of 2,906 transcripts and 584 differentially expressed genes (≥ 2 fold, p <0...
October 17, 2016: Environmental Microbiology
Kathleen McCaffrey, Ineke Braakman
The ER (endoplasmic reticulum) is the protein folding 'factory' of the secretory pathway. Virtually all proteins destined for the plasma membrane, the extracellular space or other secretory compartments undergo folding and maturation within the ER. The ER hosts a unique PQC (protein quality control) system that allows specialized modifications such as glycosylation and disulfide bond formation essential for the correct folding and function of many secretory proteins. It is also the major checkpoint for misfolded or aggregation-prone proteins that may be toxic to the cell or extracellular environment...
October 15, 2016: Essays in Biochemistry
Ignat Printsev, Daniel Curiel, Kermit L Carraway
The canonical function of the endoplasmic reticulum-associated degradation (ERAD) system is to enforce quality control among membrane-associated proteins by targeting misfolded secreted, intra-organellar, and intramembrane proteins for degradation. However, increasing evidence suggests that ERAD additionally functions in maintaining appropriate levels of a subset of membrane-associated proteins. In this 'quantity control' capacity, ERAD responds to environmental cues to regulate the proteasomal degradation of specific ERAD substrates according to cellular need...
October 14, 2016: Journal of Membrane Biology
Laura László, Balázs Sarkadi, Tamás Hegedűs
ABCG2/BCRP is a membrane protein, involved in xenobiotic and endobiotic transport in key pharmacological barriers and drug metabolizing organs, in the protection of stem cells, and in multidrug resistance of cancer. Pharmacogenetic studies implicated the role of ABCG2 in response to widely used medicines and anticancer agents, as well as in gout. Its Q141K variant exhibits decreased functional expression thus increased drug accumulation and decreased urate secretion. Still, there has been no reliable molecular model available for this protein, as the published structures of other ABC transporters could not be properly fitted to the ABCG2 topology and experimental data...
2016: PloS One
Shaoxiao Wang, Siyuan Zhang, Chuan Xu, Addie Barron, Floyd Galiano, Dhaval Patel, Yong Joo Lee, Guy A Caldwell, Kim A Caldwell, Stephan N Witt
We have been investigating the role that phosphatidylethanolamine (PE) and phosphatidylcholine (PC) content plays in modulating the solubility of the Parkinson's disease protein alpha-synuclein (α-syn) using Saccharomyces cerevisiae and Caenorhabditis elegans. One enzyme that synthesizes PE is the conserved enzyme phosphatidylserine decarboxylase (Psd1/yeast; PSD-1/worms), which is lodged in the inner mitochondrial membrane. We previously found that decreasing the level of PE due to knockdown of Psd1/psd-1 affects the homeostasis of α-syn in vivo...
2016: PloS One
Suneale Banerji, William Lawrance, Clive Metcalfe, David C Briggs, Akira Yamauchi, Omer Dushek, P Anton Van Der Merwe, Anthony J Day, David G Jackson
The lymphatic vessel endothelial receptor LYVE-1 is implicated in uptake of hyaluronan (HA) and trafficking of leucocytes to draining lymph nodes. Yet LYVE-1 has only weak affinity for hyaluronan, and depends on receptor clustering and higher-order ligand organisation for durable binding in lymphatic endothelium. An unusual feature of LYVE-1 not found in other HA receptors is the potential to form disulfide-linked homodimers. However their influence on function has not been investigated. Here we show LYVE-1 homodimers are the predominant configuration in lymphatic endothelium in vitro and in vivo and formation requires solely the unpaired cysteine residue C201 within the membrane-proximal domain, yielding a 15 fold higher HA binding affinity and ~ 70 fold slower off-rate than monomer...
October 12, 2016: Journal of Biological Chemistry
T N Figueira, L M Palermo, A S Veiga, D Huey, C A Alabi, N C Santos, J C Welsch, C Mathieu, B Horvat, S Niewiesk, A Moscona, M A R B Castanho, M Porotto
: Measles virus (MV) infection is undergoing resurgence and remains one of the leading causes of death among young children worldwide despite the availability of an effective measles vaccine. MV infects its target cells by coordinated action of the MV hemagglutinin (H) and fusion (F) envelope glycoproteins; upon receptor engagement by H, the pre-fusion F undergoes a structural transition, extending and inserting into the target cell membrane and then re-folding into a post-fusion structure that fuses the viral and cell membranes...
October 12, 2016: Journal of Virology
Sarah K McDonald, Karen Gibson Fleming
Hysteresis in equilibrium protein folding titrations is an experimental barrier that must be overcome to extract meaningful thermodynamic quantities. Traditional approaches to solving this problem involve testing a spectrum of solution conditions to find ones that achieve path independence. Through this procedure, a specific pH of 3.8 was required to achieve path-independence for the water-to-bilayer equilibrium folding of outer membrane protein OmpLA. We hypothesized that the neutralization of negatively charged side chains (Asp and Glu) at pH 3...
October 12, 2016: Biochemistry
Arunima Chaudhuri, Xavier Prasanna, Priyanka Agiru, Hirak Chakraborty, Anna Rydström, James C S Ho, Catharina Svanborg, Durba Sengupta, Amitabha Chattopadhyay
Bovine α-lactalbumin (BLA) forms cytotoxic complexes with oleic acid (OA) that perturbs tumor cell membranes, but molecular determinants of these membrane-interactions remain poorly understood. Here, we aim to obtain molecular insights into the interaction of BLA/BLA-OA complex with model membranes. We characterized the folding state of BLA-OA complex using tryptophan fluorescence and resolved residue-specific interactions of BLA with OA using molecular dynamics simulation. We integrated membrane-binding data using a voltage-sensitive probe and molecular dynamics (MD) to demonstrate the preferential interaction of the BLA-OA complex with negatively charged membranes...
October 12, 2016: Scientific Reports
Ming Liu, Li-Na Li, Yi-Ting Pan, Jian-Qiang Kong
As the first step of ongoing efforts to investigate the genes responsible for the biosynthesis of steroidal saponins in the medicinal plant Ornithogalum caudatum, this investigation reported the cDNA isolation, prokaryotic expression and functional characterization of squalene synthase (SQS) gene from O. caudatum for the first time. Specifically, two unigenes showing high sequence identity to SQS were retrieved from RNA-Taq data, and then a full-length OcSQS1 corresponding to the two unigenes was isolated from O...
October 7, 2016: Protein Expression and Purification
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