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Protein import

Wolfram C M Dempke, Peter Uciechowski, Klaus Fenchel, Timothy Chevassut
Well-balanced levels of tyrosine phosphorylation, maintained by the reversible and coordinated actions of protein tyrosine kinases (PTKs) and protein tyrosine phosphatases (PTPs), are critical for a wide range of cellular processes including growth, differentiation, metabolism, migration, and survival. Aberrant tyrosine phosphorylation, as a result of a perturbed balance between the activities of PTKs and PTPs, is linked to the pathogenesis of numerous human diseases, including cancer, suggesting that PTPs may be innovative molecular targets for cancer treatment...
June 20, 2018: Oncology
Haicen Yue, Brian A Camley, Wouter-Jan Rappel
Cell-cell communication plays an important role in collective cell migration. However, it remains unclear how cells in a group cooperatively process external signals to determine the group's direction of motion. Although the topology of signaling pathways is vitally important in single-cell chemotaxis, the signaling topology for collective chemotaxis has not been systematically studied. Here, we combine mathematical analysis and simulations to find minimal network topologies for multicellular signal processing in collective chemotaxis...
June 19, 2018: Biophysical Journal
Yuan Gao, Stephen M Anthony, Yanqi Yu, Yi Yi, Yan Yu
Intracellular cargos are transported by molecular motors along actin and microtubules, but how their dynamics depends on the complex structure of the cytoskeletal network remains unclear. In this study, we investigated this longstanding question by measuring simultaneously the rotational and translational dynamics of cargos at microtubule intersections in living cells. We engineered two-faced particles that are fluorescent on one hemisphere and opaque on the other and used their optical anisotropy to report the rotation of cargos...
June 19, 2018: Biophysical Journal
Kentaro Furukawa, Tomoyuki Fukuda, Shun-Ichi Yamashita, Tetsu Saigusa, Yusuke Kurihara, Yutaka Yoshida, Hiromi Kirisako, Hitoshi Nakatogawa, Tomotake Kanki
Mitophagy plays an important role in mitochondrial quality control. In yeast, phosphorylation of the mitophagy receptor Atg32 by casein kinase 2 (CK2) upon induction of mitophagy is a prerequisite for interaction of Atg32 with Atg11 (an adaptor protein for selective autophagy) and following delivery of mitochondria to the vacuole for degradation. Because CK2 is constitutively active, Atg32 phosphorylation must be precisely regulated to prevent unrequired mitophagy. We found that the PP2A (protein phosphatase 2A)-like protein phosphatase Ppg1 was essential for dephosphorylation of Atg32 and inhibited mitophagy...
June 19, 2018: Cell Reports
Sarah L Jaslow, Kyle D Gibbs, W Florian Fricke, Liuyang Wang, Kelly J Pittman, Mark K Mammel, Joshua T Thaden, Vance G Fowler, Gianna E Hammer, Johanna R Elfenbein, Dennis C Ko
Salmonella enterica is an important foodborne pathogen that uses secreted effector proteins to manipulate host pathways to facilitate survival and dissemination. Different S. enterica serovars cause disease syndromes ranging from gastroenteritis to typhoid fever and vary in their effector repertoire. We leveraged this natural diversity to identify stm2585, here designated sarA (Salmonella anti-inflammatory response activator), as a Salmonella effector that induces production of the anti-inflammatory cytokine IL-10...
June 19, 2018: Cell Reports
Kenji Matsuzawa, Takuya Himoto, Yuki Mochizuki, Junichi Ikenouchi
Adherens junctions (AJs) control epithelial cell behavior, such as collective movement and morphological changes, during development and in disease. However, the molecular mechanism of AJ remodeling remains incompletely understood. Here, we report that the conformational activation of α-catenin is the key event in the dynamic regulation of AJ remodeling. α-catenin activates RhoA to increase actomyosin contractility at cell-cell junctions. This leads to the stabilization of activated α-catenin, in part through the recruitment of the actin-binding proteins, vinculin and afadin...
June 19, 2018: Cell Reports
Melissa S Maginnis
Virus-receptor interactions play a key regulatory role in viral host range, tissue tropism, and viral pathogenesis. Viruses utilize elegant strategies to attach to one or multiple receptors, overcome the plasma membrane barrier, enter, and access the necessary host cell machinery. The viral attachment protein can be viewed as the "key" that unlocks host cells by interacting with the "lock" - the receptor - on the cell surface, and these lock-and-key interactions are critical for viruses to successfully invade host cells...
June 17, 2018: Journal of Molecular Biology
Yang Qi, Jeffrey W Martin, Adam W Barb, François Thélot, Anthony Yan, Bruce R Donald, Terrence G Oas
The flexibility of biological macromolecules is an important structural determinant of function. Unfortunately, the correlations between different motional modes are poorly captured by discrete ensemble representations. Here, we present new ways to both represent and visualize correlated interdomain motions. Interdomain motions are determined directly from residual dipolar couplings (RDCs), represented as a continuous conformational distribution, and visualized using the disk-on-sphere (DoS) representation...
June 17, 2018: Journal of Molecular Biology
Eric A Miller, Yara Jabbour Al Maalouf, Hadley D Sikes
In this work, we characterize the impact of large-volume processing upon the analytical sensitivity of flow-through paper-based immunoassays. Larger sample volumes feature greater molar quantities of available analyte, but the assay design principles which would enable the rapid collection of this dilute target are ill-defined. We developed a finite-element model to explore the operat-ing conditions under which processing large sample volumes via pressure-driven convective flow would yield improved binding signal...
June 20, 2018: Analytical Chemistry
Ann S Thomas, Arjen M Krikken, Rinse de Boer, Chris Williams
Saccharomyces cerevisiae Aat2p contains a peroxisomal targeting signal type-1 and localises to peroxisomes in oleate-grown cells, but not in glucose-grown cells. Here, we have investigated Aat2p from the yeast Hansenula polymorpha, which lacks a recognizable peroxisomal targeting signal. Aat2p tagged with GFP at its C-terminus displays a dual cytosol-peroxisome localisation in ethanol-grown cells. The partial peroxisomal localization of Aat2p persisted in the absence of the classical cycling receptors Pex5p and Pex7p but Aat2p targeting to peroxisomes was reduced in cells deleted for the matrix protein import factors PEX1, PEX2 and PEX13...
June 20, 2018: FEBS Letters
Francisco Garrido, María Pacheco, Rocío Vargas-Martínez, Roberto Velasco-García, Inmaculada Jorge, Horacio Serrano, Francisco Portillo, Jesús Vázquez, María Ángeles Pajares
Protein-protein interactions are an important mechanism for the regulation of enzyme function allowing metabolite channeling, crosstalk between pathways or the introduction of post-translational modifications. Therefore, a number of high-throughput studies have been carried out to shed light on the protein networks established under different pathophysiological settings. Surprisingly, this type of information is quite limited for enzymes of intermediary metabolism such as betaine homocysteine S-methyltransferase, despite its high hepatic abundancy and its role in homocysteine metabolism...
2018: PloS One
Jie Zeng, Yajie Hu, Tian Jia, Ruiyao Zhang, Tongchao Su, Junliang Sun, Haiyan Gao, Guanglei Li, Meng Cao, Mengdi Song
BACKGROUND: Sialylated glycoconjugates play important roles in physiological and pathological processes. However, available sialylated oligosaccharides source is limited which is a barrier to study their biological roles. This work reports an efficient approach to produce sialic acid-modified lactuloses and investigates their inhibitory effects on Staphylococcus aureus (S. aureus). METHODS: A one-pot two-enzyme (OPTE) sialylation system was used to efficiently synthesize sialylated lactuloses...
2018: PloS One
Sambit Kumar Mishra, Robert L Jernigan
Dynamic communities in proteins comprise the cohesive structural units that individually exhibit rigid body motions. These can correspond to structural domains, but are usually smaller parts that move with respect to one another in a protein's internal motions, key to its functional dynamics. Previous studies emphasized their importance to understand the nature of ligand-induced allosteric regulation. These studies reported that mutations to key community residues can hinder transmission of allosteric signals among the communities...
2018: PloS One
Jianfa Jiang, Kenan Yu, Zhaoying Jiang, Min Xue
Endometriosis (EMs) is a chronic inflammatory condition. Interleukin (IL)-37 is a member of the IL-1 family and an anti-inflammatory cytokine. This study aimed to evaluate the possible role of IL-37 in the EMs pathogenesis. We investigated the in vivo effect of IL-37 on EMs by injection with recombinant human IL-37 (rhIL-37) into EMs mice. Furthermore, we evaluated the in-vitro effects of IL-37 on proliferation, adhesion, migration, and invasiveness of endometrial stromal cells (ESCs), and explored whether Wnt/β-catenin and mitogen-activated protein kinase (MAPK) pathways were involved in this process...
June 1, 2018: Biological Chemistry
Alice Crane, Sudhir Isharwal, Hui Zhu
The field of urology encompasses all benign and malignant disorders of the urinary tract and male genital tract. Together, urological disorders convey a huge economic and patient quality-of-life burden. Furthermore, hospital acquired urinary tract infections are coming under scrutiny as a measure of hospital quality. Given the importance of these pathologies, there is much progress still to be made in drug delivery designed to minimize side effects while providing effective care. Bladder pathology, in particular poses a unique opportunity for the development of novel intravesical therapies that can avoid some of the pitfalls of systemic drug delivery...
June 20, 2018: Molecular Pharmaceutics
Changqi Liu, Shridhar Krishna Sathe
With the increased global awareness and rise in food allergies, a multifold interest in food allergens is evident. The presence of undeclared food allergens results in expensive food recalls and increase risks of anaphylaxis for the sensitive individuals. Regardless of the allergenic food, the immunogen needs to be identified and detected before making any efforts to inactivate/eliminate it. In type I food allergies, protein immunogen cross-links IgEs leading to basophil/mast cell degranulation resulting in the symptoms that range from mild irritation to anaphylaxis...
June 20, 2018: Journal of Agricultural and Food Chemistry
Udita Brahmachari, Zhanjun Guo, Sara E Konecny, Emmanuela N C Obi, Bridgette A Barry
Photosystem II oxidizes water at a Mn4 CaO5 cluster. Oxygen evolution is accompanied by proton release through a 35 Å hydrogen-bonding network to the lumen. The mechanism of this proton-transfer reaction is not known, but the reaction is dependent on chloride. Here, vibrational spectroscopy defines the functional properties of the proton-transfer network using chloride, bromide, and nitrate as perturbative agents. As assessed by peptide C═O frequencies, bromide substitution yields a spectral Stark shift because of its increase in ionic radius...
June 20, 2018: Journal of Physical Chemistry. B
Toshihiko Sugiki, Kyoko Furuita, Toshimichi Fujiwara, Chojiro Kojima
Amino acid selective isotope labeling is an important nuclear magnetic resonance technique, especially for larger proteins, providing strong bases for the unambiguous resonance assignments and information concerning the structure, dynamics, and intermolecular interactions. Amino acid selective 15 N labeling suffers from isotope dilution caused by metabolic interconversion of the amino acids, resulting in isotope scrambling within the target protein. Carbonyl 13 C atoms experience less isotope scrambling than the main-chain 15 N atoms do...
June 20, 2018: Biochemistry
Nicholas M Riley, Jacek W Sikora, Henrique S Seckler, Joseph B Greer, Ryan T Fellers, Richard D LeDuc, Michael S Westphall, Paul M Thomas, Neil L Kelleher, Joshua J Coon
High-throughput top-down proteomic experiments directly identify proteoforms in complex mixtures, making high quality tandem mass spectra necessary to deeply characterize proteins with many sources of variation. Collision-based dissociation methods offer expedient data acquisition, but often fail to extensively fragment proteoforms for thorough analysis. Electron-driven dissociation methods are a popular alternative approach, especially for precursor ions with high charge density. Combining infrared photo-activation concurrent with electron transfer dissociation (ETD) reactions, i...
June 20, 2018: Analytical Chemistry
Mark D Ericson, Zoe M Koerperich, Katie T Freeman, Katlyn A Fleming, Carrie Haskell-Luevano
The melanocortin-3 and melanocortin-4 receptors (MC3R and MC4R), endogenous agonists derived from the proopiomelanocortin gene transcript, and naturally-occurring antagonists agouti and agouti-related protein (AGRP) have been linked to biological pathways associated with energy homeostasis. The active tripeptide sequence of AGRP, Arg111-Phe112-Phe113, is located on a hypothesized β-hairpin loop. Herein, stereochemical modifications of the Arg-Phe-Phe sequence were examined in the octapeptide AGRP-derived macrocyclic scaffold c[Pro-Arg-Phe-Phe-Xxx-Ala-Phe-DPro], where Xxx was Asn or diaminopropionic acid (Dap)...
June 20, 2018: ACS Chemical Neuroscience
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