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Amy H Andreotti, Raji E Joseph, James M Conley, Janet Iwasa, Leslie J Berg
Signaling through the T cell antigen receptor (TCR) activates a series of tyrosine kinases. Directly associated with the TCR, the SRC family kinase LCK and the SYK family kinase ZAP-70 are essential for all downstream responses to TCR stimulation. In contrast, the TEC family kinase ITK is not an obligate component of the TCR cascade. Instead, ITK functions as a tuning dial, to translate variations in TCR signal strength into differential programs of gene expression. Recent insights into TEC kinase structure have provided a view into the molecular mechanisms that generate different states of kinase activation...
April 26, 2018: Annual Review of Immunology
Nathan Gamarra, Stephanie L Johnson, Michael J Trnka, Alma L Burlingame, Geeta J Narlikar
ISWI family chromatin remodeling motors use sophisticated autoinhibition mechanisms to control nucleosome sliding. Yet how the different autoinhibitory domains are regulated is not well understood. Here we show that an acidic patch formed by histones H2A and H2B of the nucleosome relieves the autoinhibition imposed by the AutoN and the NegC regions of the human ISWI remodeler SNF2h. Further, by single molecule FRET we show that the acidic patch helps control the distance travelled per translocation event. We propose a model in which the acidic patch activates SNF2h by providing a landing pad for the NegC and AutoN auto-inhibitory domains...
April 17, 2018: ELife
Aaron A Cook, Wei Deng, Jinqi Ren, Renhao Li, John Sondek, Wolfgang Bergmeier
Platelets are recruited to sites of vascular injury where they are activated and aggregate to form a hemostatic plug. This process requires the activation of the small GTPase Rap1B by its cognate guanine nucleotide exchange factor CalDAG-GEFI. Studies on platelet function suggest that CalDAG-GEFI activity is regulated by changes in cytosolic calcium, but the exact molecular mechanism is poorly understood. Here, we show that purified CalDAG-GEFI is autoinhibited and directly regulated by calcium. Substitutions of putative calcium-binding residues within the canonical EF hands of CalDAG-GEFI diminish its capacity to activate Rap1B...
April 5, 2018: Journal of Biological Chemistry
Kai Wang, Junna He, Yang Zhao, Ting Wu, Xiaofeng Zhou, Yanglin Ding, Lingyao Kong, Xiaoji Wang, Yu Wang, Jigang Li, Chun-Peng Song, Bao-Shan Wang, Shuhua Yang, Jian-Kang Zhu, Zhizhong Gong
The reversible phosphorylation of proteins by kinases and phosphatases is an antagonistic process that modulates many cellular functions. Protein phosphatases are usually negatively regulated by inhibitor proteins. During abscisic acid (ABA) signaling, these inhibitor proteins comprise PYR1/PYL/RCAR ABA receptors, which inhibit the core negative regulators, the clade A type 2C protein phosphatases (PP2Cs). However, it is not known whether these PP2Cs are positively regulated by other proteins. Here, we identified an Arabidopsis thaliana ear1 (enhancer of aba co-receptor 1) mutant that exhibits pleiotropic ABA-hypersensitive phenotypes...
April 4, 2018: Plant Cell
David R Paquette, Ryan W Tibble, Tristan S Daifuku, John D Gross
5' mediated cytoplasmic RNA decay is a conserved cellular process in eukaryotes. While the functions of the structured core domains in this pathway are well-studied, the role of abundant intrinsically disordered regions (IDRs) is lacking. Here we reconstitute the Dcp1:Dcp2 complex containing a portion of the disordered C-terminus and show its activity is autoinhibited by linear interaction motifs. Enhancers of decapping (Edc) 1 and 3 cooperate to activate decapping by different mechanisms: Edc3 alleviates autoinhibition by binding IDRs and destabilizing an inactive form of the enzyme, whereas Edc1 stabilizes the transition state for catalysis...
March 29, 2018: Nucleic Acids Research
Thomas Vogl, Athanasios Stratis, Viktor Wixler, Tom Völler, Sumita Thurainayagam, Selina K Jorch, Stefanie Zenker, Alena Dreiling, Deblina Chakraborty, Mareike Fröhling, Peter Paruzel, Corinna Wehmeyer, Sven Hermann, Olympia Papantonopoulou, Christiane Geyer, Karin Loser, Michael Schäfers, Stephan Ludwig, Monika Stoll, Tomas Leanderson, Joachim L Schultze, Simone König, Thomas Pap, Johannes Roth
Autoimmune diseases, such as psoriasis and arthritis, show a patchy distribution of inflammation despite systemic dysregulation of adaptive immunity. Thus, additional tissue-derived signals, such as danger-associated molecular patterns (DAMPs), are indispensable for manifestation of local inflammation. S100A8/S100A9 complexes are the most abundant DAMPs in many autoimmune diseases. However, regulatory mechanisms locally restricting DAMP activities are barely understood. We now unravel for the first time, to our knowledge, a mechanism of autoinhibition in mice and humans restricting S100-DAMP activity to local sites of inflammation...
April 3, 2018: Journal of Clinical Investigation
Thomas M Moon, Jessica L Sheehe, Praveena Nukareddy, Lydia W Nausch, Jessica Wohlfahrt, Dwight E Matthews, Donald K Blumenthal, Wolfgang R Dostmann
The type I cGMP-dependent protein kinases serve essential physiological functions, including smooth muscle relaxation, cardiac remodeling, and platelet aggregation. These enzymes form homodimers through their N-terminal dimerization domains, a feature implicated in regulating their cooperative activation. Previous investigations into the activation mechanisms of PKG I isoforms have been largely influenced by structures of the cAMP-dependent protein kinase (PKA). Here, we examined PKG Iα activation by cGMP and cAMP by engineering a monomeric form that lacks N-terminal residues 1-53 (Δ53)...
March 30, 2018: Journal of Biological Chemistry
Zhonghua Liu, Chuanping Wang, Joseph K Rathkey, Jie Yang, George R Dubyak, Derek W Abbott, Tsan Sam Xiao
Pyroptosis is an inflammatory form of programmed cell death that plays important roles in immune protection against infections and in inflammatory disorders. Gasdermin D (GSDMD) is an executor of pyroptosis upon cleavage by caspases-1/4/5/11 following canonical and noncanonical inflammasome activation. GSDMD N-terminal domain assembles membrane pores to induce cytolysis, whereas its C-terminal domain inhibits cell death through intramolecular association with the N domain. The molecular mechanisms of autoinhibition for GSDMD are poorly characterized...
March 14, 2018: Structure
Tenpei Akita, Kazushi Aoto, Mitsuhiro Kato, Masaaki Shiina, Hiroki Mutoh, Mitsuko Nakashima, Ichiro Kuki, Shin Okazaki, Shinichi Magara, Takashi Shiihara, Kenji Yokochi, Kaori Aiba, Jun Tohyama, Chihiro Ohba, Satoko Miyatake, Noriko Miyake, Kazuhiro Ogata, Atsuo Fukuda, Naomichi Matsumoto, Hirotomo Saitsu
Objective: α ( CAMK2A ) and β ( CAMK2B ) isoforms of Calcium/calmodulin-dependent protein kinase II (CaMKII) play a pivotal role in neuronal plasticity and in learning and memory processes in the brain. Here, we explore the possible involvement of α - and β -CaMKII variants in neurodevelopmental disorders. Methods: Whole-exome sequencing was performed for 976 individuals with intellectual disability, developmental delay, and epilepsy. The effect of CAMK2A and CAMK2B variants on CaMKII structure and firing of neurons was evaluated by computational structural analysis, immunoblotting, and electrophysiological analysis...
March 2018: Annals of Clinical and Translational Neurology
Tales Rocha de Moura, Sina Mozaffari-Jovin, Csaba Zoltán Kibédi Szabó, Jana Schmitzová, Olexandr Dybkov, Constantin Cretu, Michael Kachala, Dmitri Svergun, Henning Urlaub, Reinhard Lührmann, Vladimir Pena
Human nineteen complex (NTC) acts as a multimeric E3 ubiquitin ligase in DNA repair and splicing. The transfer of ubiquitin is mediated by Prp19-a homotetrameric component of NTC whose elongated coiled coils serve as an assembly axis for two other proteins called SPF27 and CDC5L. We find that Prp19 is inactive on its own and have elucidated the structural basis of its autoinhibition by crystallography and mutational analysis. Formation of the NTC core by stepwise assembly of SPF27, CDC5L, and PLRG1 onto the Prp19 tetramer enables ubiquitin ligation...
March 15, 2018: Molecular Cell
Yoshinori Hirano, Yu Amano, Shigenobu Yonemura, Toshio Hakoshima
Mechanotransduction by α-catenin facilitates the force-dependent development of adherens junctions (AJs) by recruiting vinculin to reinforce actin anchoring of AJs. The α-catenin mechanotransducing action is facilitated by its force-sensing device region that autoinhibits the vinculin-binding site 1 (VBS1). Here, we report the high-resolution structure of the force-sensing device region of α-catenin, which shows the autoinhibited form comprised of helix bundles E, F and G. The cryptic VBS1 is embedded into helix bundle E stabilized by direct interactions with the autoinhibitory region forming helix bundles F and G...
March 15, 2018: Genes to Cells: Devoted to Molecular & Cellular Mechanisms
Jacob D Aguirre, Karen M Dunkerley, Rica Lam, Michele Rusal, Gary S Shaw
Autosomal recessive juvenile Parkinsonism (ARJP) is an inherited neurodegenerative disease in which 50% of affected individuals harbor mutations in the gene encoding the E3 ligase parkin. Parkin regulates the mitochondrial recycling pathway, which is induced by oxidative stress. In its native state, parkin is autoinhibited by its N-terminal ubiquitin-like (Ubl) domain which blocks the binding site for an incoming E2~ubiquitin conjugate, needed for parkin's ubiquitination activity. Parkin is activated via phosphorylation of Ser65 in its Ubl domain by PTEN-induced putative kinase 1 (PINK1) and an ubiquitin molecule phosphorylated at a position equivalent to Ser65 in parkin...
March 12, 2018: Journal of Biological Chemistry
Soung-Hun Roh, Nicholas J Stam, Corey F Hryc, Sergio Couoh-Cardel, Grigore Pintilie, Wah Chiu, Stephan Wilkens
The molecular mechanism of transmembrane proton translocation in rotary motor ATPases is not fully understood. Here, we report the 3.5-Å resolution cryoEM structure of the lipid nanodisc-reconstituted Vo proton channel of the yeast vacuolar H+ -ATPase, captured in a physiologically relevant, autoinhibited state. The resulting atomic model provides structural detail for the amino acids that constitute the proton pathway at the interface of the proteolipid ring and subunit a. Based on the structure and previous mutagenesis studies, we propose the chemical basis of transmembrane proton transport...
March 15, 2018: Molecular Cell
Diego Butera, Freda Passam, Lining Ju, Kristina M Cook, Heng Woon, Camilo Aponte-Santamaría, Elizabeth Gardiner, Amanda K Davis, Deirdre A Murphy, Agnieszka Bronowska, Brenda M Luken, Carsten Baldauf, Shaun Jackson, Robert Andrews, Frauke Gräter, Philip J Hogg
Force-dependent binding of platelet glycoprotein Ib (GPIb) receptors to plasma von Willebrand factor (VWF) plays a key role in hemostasis and thrombosis. Previous studies have suggested that VWF activation requires force-induced exposure of the GPIb binding site in the A1 domain that is autoinhibited by the neighboring A2 domain. However, the biochemical basis of this "mechanopresentation" remains elusive. From a combination of protein chemical, biophysical, and functional studies, we find that the autoinhibition is controlled by the redox state of an unusual disulfide bond near the carboxyl terminus of the A2 domain that links adjacent cysteine residues to form an eight-membered ring...
February 2018: Science Advances
Guillaume Combes, Helena Barysz, Chantal Garand, Luciano Gama Braga, Ibrahim Alharbi, Philippe Thebault, Luc Murakami, Dominic P Bryne, Stasa Stankovic, Patrick A Eyers, Victor M Bolanos-Garcia, William C Earnshaw, John Maciejowski, Prasad V Jallepalli, Sabine Elowe
Monopolar spindle 1 (Mps1) is a conserved apical kinase in the spindle assembly checkpoint (SAC) that ensures accurate segregation of chromosomes during mitosis. Mps1 undergoes extensive auto- and transphosphorylation, but the regulatory and functional consequences of these modifications remain unclear. Recent findings highlight the importance of intermolecular interactions between the N-terminal extension (NTE) of Mps1 and the Hec1 subunit of the NDC80 complex, which control Mps1 localization at kinetochores and activation of the SAC...
February 20, 2018: Current Biology: CB
Yumi Matsui, Isao Yasumatsu, Ken Ichi Yoshida, Shin Iimura, Yutaka Ikeno, Takako Nawano, Hajime Fukano, Osamu Ubukata, Hiroyuki Hanzawa, Fumie Tanzawa, Takeshi Isoyama
Mitogen-activated protein kinase (MAPK)-interacting kinases 1 (Mnk1) and 2 (Mnk2) modulate translation initiation through the phosphorylation of eukaryotic translation initiation factor 4E, which promotes tumorigenesis. However, Mnk1 and Mnk2 are dispensable in normal cells, suggesting that the inhibition of Mnk1 and Mnk2 could be effective in cancer therapy. To provide a structural basis for Mnk1 inhibition, a novel Mnk1 inhibitor was discovered and the crystal structure of Mnk1 in complex with this inhibitor was determined...
March 1, 2018: Acta Crystallographica. Section F, Structural Biology Communications
Guanqiao Wang, Mingzhen Zhang, Hyunbum Jang, Shaoyong Lu, Shizhou Lin, Guo-Qiang Chen, Ruth Nussinov, Jian Zhang, Vadim Gaponenko
Calmodulin (CaM) is a calcium sensor protein that directly interacts with the dual specificity (lipid and protein) kinase PI3Kα through the SH2 domains of the p85 regulatory subunit. In adenocarcinomas, the CaM interaction removes the autoinhibition of the p110 catalytic subunit of PI3Kα, leading to activation of PI3Kα and promoting cell proliferation, survival, and migration. Here we demonstrate that the cSH2 domain of p85α engages its two CaM binding motifs in the interaction with the N- and C-lobes of CaM as well as the flexible central linker and our NMR experiments provide structural details...
March 1, 2018: Biochemistry
Marie-France Langelier, Levani Zandarashvili, Pedro M Aguiar, Ben E Black, John M Pascal
PARP-1 cleaves NAD+ and transfers the resulting ADP-ribose moiety onto target proteins and onto subsequent polymers of ADP-ribose. An allosteric network connects PARP-1 multi-domain detection of DNA damage to catalytic domain structural changes that relieve catalytic autoinhibition; however, the mechanism of autoinhibition is undefined. Here, we show using the non-hydrolyzable NAD+ analog benzamide adenine dinucleotide (BAD) that PARP-1 autoinhibition results from a selective block on NAD+ binding. Following DNA damage detection, BAD binding to the catalytic domain leads to changes in PARP-1 dynamics at distant DNA-binding surfaces, resulting in increased affinity for DNA damage, and providing direct evidence of reverse allostery...
February 27, 2018: Nature Communications
Emily F Ruff, Joseph M Muretta, Andrew R Thompson, Eric W Lake, Soreen Cyphers, Steven K Albanese, Sonya M Hanson, Julie M Behr, David D Thomas, John D Chodera, Nicholas M Levinson
Many eukaryotic protein kinases are activated by phosphorylation on a specific conserved residue in the regulatory activation loop, a post-translational modification thought to stabilize the active DFG-In state of the catalytic domain. Here we use a battery of spectroscopic methods that track different catalytic elements of the kinase domain to show that the ~100-fold activation of the mitotic kinase Aurora A (AurA) by phosphorylation occurs without a population shift from the DFG-Out to the DFG-In state, and that the activation loop of the activated kinase remains highly dynamic...
February 21, 2018: ELife
Leah B Gerrard, Malinda L S Tantirigama, John M Bekkers
The piriform cortex (PC), like other cortical regions, normally operates in a state of dynamic equilibrium between excitation and inhibition. Here we examined the roles played by pre- and postsynaptic GABAB receptors in maintaining this equilibrium in the PC. Using whole-cell recordings in brain slices from the anterior PC of mice, we found that synaptic activation of postsynaptic GABAB receptors hyperpolarized the two major classes of layer 2 principal neurons and reduced the intrinsic electrical excitability of these neurons...
2018: Frontiers in Cellular Neuroscience
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