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FEBS Letters

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https://www.readbyqxmd.com/read/27914170/water-influx-via-aquaporin-directly-determines-necrotic-cell-death-induced-by-the-bacillus-thuringiensis-cry-toxin
#1
LETTER
Haruka Endo, Masaaki Azuma, Satomi Adegawa, Shingo Kikuta, Ryoichi Sato
The Bacillus thuringiensis Cry toxin causes swelling and necrosis in insect cells, but the route(s) and significance of the water influx involved in its cytotoxicity are unclear. Here, we assessed the role of aquaporins (AQPs), known as water channels, in Cry toxin intoxication. An AQP inhibitor did not interfere with any known process to form the toxin pore, but it diminished the cell swelling and loss of membrane integrity induced by the Cry toxin. Overexpression of AQPs facilitated water influx and cytotoxicity...
December 3, 2016: FEBS Letters
https://www.readbyqxmd.com/read/27914169/crystal-structure-of-pkg-i%C3%AE-cnb-b-rp-cgmps-complex-reveals-an-apo-like-inactive-conformation
#2
LETTER
James C Campbell, Bryan VanSchouwen, Robin Lorenz, Banumathi Sankaran, Friedrich W Herberg, Giuseppe Melacini, Choel Kim
The R-enantiomer of phosphorothioate analogs of cGMP, Rp-cGMPS, is one of few known inhibitors of cGMP-dependent protein kinase I (PKG I); however, its mechanism of inhibition is currently not fully understood. Here, we determined the crystal structure of the PKG Iβ cyclic nucleotide-binding domain (PKG Iβ CNB-B), considered a 'gatekeeper' for cGMP activation, bound to Rp-cGMPS at 1.3 Å. Our structural and NMR data show that PKG Iβ CNB-B bound to Rp-cGMPS displays an apo-like structure with its helical domain in an open conformation...
December 3, 2016: FEBS Letters
https://www.readbyqxmd.com/read/27889905/ligand-binding-and-conformational-dynamics-in-a-flavin-based-electron-bifurcating-enzyme-complex-revealed-by-hdx-ms
#3
LETTER
Julius Konstantin Demmer, Fiona Rupprecht, Martin Lorenz Eisinger, Ulrich Ermler, Julian David Langer
Flavin-based-electron-bifurcation (FBEB) is a novel mechanism of energy coupling used by anaerobic microorganisms to optimize their energy metabolism efficiency. The first high-resolution structure of a complete FBEB enzyme complex, the NADH-dependent-reduced-ferredoxin:NADP(+) -oxidoreductase (NfnAB) of Thermotoga maritima, was recently solved. However, no experimental evidence for the NADPH-binding site and conformational changes during the FBEB reaction are available. Here we analysed ligand binding and the conformational dynamics of oxygen-sensitive NfnAB using Hydrogen-Deuterium-eXchange-mass-spectrometry, including a customized anaerobic workflow...
November 27, 2016: FEBS Letters
https://www.readbyqxmd.com/read/27883176/mir-429-is-involved-in-regulation-of-nf-%C3%AE%C2%BAb-activity-by-targeting-ikk%C3%AE-and-suppresses-oncogenic-activity-in-cervical-cancer-cells
#4
LETTER
Jing-Yi Fan, Ya-Jie Fan, Xiang-Ling Wang, Hong Xie, Hui-Jie Gao, Yi Zhang, Min Liu, Hua Tang
Dysregulation of microRNAs (miRNAs) can contribute to tumorigenesis in cancers. In this study, we found that miR-429 was downregulated in cervical cancer tissues and suppressed cell viability and proliferation while promoting apoptosis in cervical cancer cells. IKKβ was a novel target gene of miR-429 and ectopic expression of IKKβ abrogated the phenotypes induced by miR-429. When IKKβ was downregulated by miR-429, nuclear factor κB (NF-κB) pathway activation, interleukin-6 (IL-6) and interferon-β (IFN-β) production were decreased in cervical cancer cells...
November 24, 2016: FEBS Letters
https://www.readbyqxmd.com/read/27880001/oligomeric-form-of-ctbp-coactivates-neurod1-mediated-transcription
#5
LETTER
Subir K Ray, H Joyce Li, Andrew B Leiter
The mechanism underlying transcriptional coactivation by the co-repressor CtBP is not established. We previously found that CtBP co-occupies several actively transcribed endocrine genes with the transcription factor NeuroD1 to paradoxically increase transcription by recruiting KDM1A and CoREST. While the importance of the oligomeric form of CtBP for corepression is well established, the role of oligomerization in transcriptional coactivation has received little attention. Here, we examined the importance of the oligomeric state of CtBP for coactivation of NeuroD1-dependent transcription by expressing a CtBP dimerization mutant in cells depleted of endogenous CtBP...
November 23, 2016: FEBS Letters
https://www.readbyqxmd.com/read/27878994/direct-observation-of-a-deoxyadenosyl-radical-in-an-active-enzyme-environment
#6
LETTER
Lorenz Heidinger, Andrea Kneuttinger, Gengo Kashiwazaki, Stefan Weber, Thomas Carell, Erik Schleicher
5'-deoxyadenosyl radicals have been proposed as the first common intermediate in the molecular reaction mechanism of the family of radical S-adenosyl-L-methionine (SAM) enzymes. However, this radical species has not yet been directly observed in a catalytically active enzyme environment. In a reduced and SAM-containing C140A mutant of the spore photoproduct lyase from Geobacillus thermodenitrificans, a mutant with altered catalytic activity, we were able to identify an organic radical with pronounced hyperfine structure using EPR spectroscopy...
November 23, 2016: FEBS Letters
https://www.readbyqxmd.com/read/27878989/discovery-and-biological-characterization-of-potent-myeloid-cell-leukemia-1-mcl-1-inhibitors
#7
LETTER
Taekyu Lee, Zhiguo Bian, Bin Zhao, Leah J Hogdal, John L Sensintaffar, Craig M Goodwin, Johannes Belmar, Subrata Shaw, James C Tarr, Nagarathanam Veerasamy, Shannon M Matulis, Brian Koss, Melissa A Fischer, Allison L Arnold, DeMarco V Camper, Carrie F Browning, Olivia W Rossanese, Amit Budhraja, Joseph Opferman, Lawrence H Boise, Michael R Savona, Anthony Letai, Edward T Olejniczak, Stephen W Fesik
Mcl-1 is an anti-apoptotic member of the Bcl-2 family of proteins that when overexpressed is associated with high tumor grade, poor survival, and resistance to chemotherapy. Mcl-1 is amplified in many human cancers, and knockdown of Mcl-1 using RNAi can lead to apoptosis. Thus, Mcl-1 is a promising cancer target. Here, we describe the discovery of picomolar Mcl-1 inhibitors that cause caspase activation, mitochondrial depolarization, and selective growth inhibition. These compounds represent valuable tools to study the role of Mcl-1 in cancer and serve as useful starting points for the discovery of clinically useful Mcl-1 inhibitors...
November 23, 2016: FEBS Letters
https://www.readbyqxmd.com/read/27878988/identification-of-a-rhodanese-like-protein-involved-in-thiouridine-biosynthesis-in-thermus-thermophilus-trna
#8
LETTER
Naoki Shigi, Shin-Ichi Asai, Kimitsuna Watanabe
Incorporation of a sulfur atom into 2-thioribothymidine (s(2) T or 5-methyl-2-thiouridine, m(5) s(2) U) at position 54 in thermophile tRNA is accomplished by an elaborate system composed of many proteins which confers thermostability to the translation system. We identified ttuD (tRNA-two-thiouridine D) as a gene for the synthesis of s(2) T54 in Thermus thermophilus. The rhodanese-like protein TtuD enhances the activity of cysteine desulfurases and receives the persulfide generated by cysteine desulfurases in vitro...
November 23, 2016: FEBS Letters
https://www.readbyqxmd.com/read/27878987/identification-and-characterization-of-circular-rnas-in-zebrafish
#9
LETTER
Yudong Shen, Xianwu Guo, Weimin Wang
Circular RNA (circRNA), a class of RNAs with circular structure, has received little attention until recently, when some new features and functions were discovered. Here, we sequenced circRNAs in zebrafish (Danio rerio) and identified 3868 circRNAs by using three algorithms (find_circ, CIRI, segemehl). The analysis of miRNA target sites on circRNAs shows that some circRNAs may function as miRNA sponges. Furthermore, we identified that reverse complementary sequences exist in the flanking regions of only 25 (2...
November 23, 2016: FEBS Letters
https://www.readbyqxmd.com/read/27859250/both-bulk-and-cancer-stem-cell-subpopulations-in-triple-negative-breast-cancer-are-susceptible-to-wnt-hdac-and-er%C3%AE-co-inhibition
#10
LETTER
Andrew Sulaiman, Brandon Sulaiman, Lara Khouri, Sarah McGarry, Carolyn Nessim, Angel Arnaout, Xuguang Li, Christina Addison, Jim Dimitroulakos, Lisheng Wang
Development of targeted therapies for triple-negative breast cancer (TNBC, a more aggressive subtype) is an unmet medical need. We analyzed data from 887 patients with invasive breast cancer and observed that increased Wnt and histone deacetylase (HDAC) activities are associated with estrogen receptor 1 (ESR1) and progesterone receptor (PGR) repression, poor survival, and increased relapse. The inverse correlation between Wnt signaling and repression of ESR1 and PGR expression was found to be magnified in cancer stem cell (CSC) subpopulations in TNBC cell lines...
November 17, 2016: FEBS Letters
https://www.readbyqxmd.com/read/27859223/selenoprotein-p-neutralizes-lipopolysaccharide-and-participates-in-hepatic-cell-endoplasmic-reticulum-stress-response
#11
LETTER
Yongzhong Zhao, Shuvojit Banerjee, Ping Huang, Xinning Wang, Candece L Gladson, Warren D Heston, Charles B Foster
Low serum selenium or selenoprotein P (SePP) levels have been repetitively observed in severe sepsis. The role of SePP in sepsis is incompletely characterized. To test the hypothesis that lipopolysaccharide (LPS) interacts with SePP, we investigated the interaction between LPS and the histidine-rich (His-rich) regions of SePP. We demonstrate that both purified SePP and synthetic peptides corresponding to the His-rich motifs neutralized LPS. In addition, we used a hepatocyte model to study the fate of SePP in response to LPS or endoplasmic reticulum (ER) stress...
November 17, 2016: FEBS Letters
https://www.readbyqxmd.com/read/27859138/heme-binding-and-peroxidase-activity-of-a-secreted-minicatalase
#12
LETTER
Giulia Mori, Nicola Doniselli, Federica Faroldi, Riccardo Percudani
Microbial pathogens often require efficient and robust H2 O2 scavenger activities to survive in the presence of reactive oxygen species generated by inflammatory responses. In addition to catalases and peroxidases, enzymes known to scavenge H2 O2 , a novel class of secreted minicatalases has been described in diderm bacteria. Here, we characterize the Helicobacter pylori (Hp) minicatalase: a monomeric hemoprotein with catalase core homology. Overexpression of Hp minicatalase rescued a catalase/peroxidase deficient E...
November 17, 2016: FEBS Letters
https://www.readbyqxmd.com/read/27859061/an-allosteric-site-enables-fine-tuning-of-cathepsin-k-by-diverse-effectors
#13
LETTER
Marko Novinec, Mateja Rebernik, Brigita Lenarčič
The cysteine peptidase cathepsin K is a potent collagenolytic enzyme and a promising target for the treatment of osteoporosis. Here, we characterize its allosteric fine-tuning via a recently identified allosteric site. We show that compound NSC94914 binds this site and acts as a specific partial inhibitor of the collagenolytic activity of cathepsin K. We link the functional differences between NSC94914 and known effectors (compound NSC11345 and glycosaminoglycans) to their different modes of interaction with the site...
November 17, 2016: FEBS Letters
https://www.readbyqxmd.com/read/27859055/identification-of-a-classic-nuclear-localization-signal-at-the-n-terminus-that-regulates-the-subcellular-localization-of-rbfox2-isoforms-during-differentiation-of-nmumg-and-p19-cells
#14
LETTER
Manuel Wenzel, Martin Schüle, Sonia Casanovas, Dennis Strand, Susanne Strand, Jennifer Winter
Nuclear localization of the alternative splicing factor Rbfox2 is achieved by a C-terminal nuclear localization signal (NLS) which can be excluded from some Rbfox2 isoforms by alternative splicing. While this predicts nuclear and cytoplasmic localization, Rbfox2 is exclusively nuclear in some cell types. Here, we identify a second NLS in the N terminus of Rbfox2 isoform 1A that is not included in Rbfox2 isoform 1F. Rbfox2 1A isoforms lacking the C-terminal NLS are nuclear, whereas equivalent 1F isoforms are cytoplasmic...
November 17, 2016: FEBS Letters
https://www.readbyqxmd.com/read/27859051/cytosolic-iron-sulfur-cluster-transfer-a-proposed-kinetic-pathway-for-reconstitution-of-glutaredoxin-3
#15
LETTER
Christine Wachnowsky, Insiya Fidai, James A Cowan
Iron-sulfur (Fe-S) clusters are ubiquitously conserved and play essential cellular roles. The mechanism of Fe-S cluster biogenesis involves multiple proteins in a complex pathway. Cluster biosynthesis primarily occurs in the mitochondria, but key Fe-S proteins also exist in the cytosol. One such protein, glutaredoxin 3 (Grx3), is involved in iron regulation, sensing, and mediating [2Fe-2S] cluster delivery to cytosolic protein targets, but the cluster donor for cytosolic Grx3 has not been elucidated. Herein, we delineate the kinetic transfer of [2Fe-2S] clusters into Grx3 from potential cytosolic carrier/scaffold proteins, IscU and Nfu, to evaluate a possible model for Grx3 reconstitution in vivo...
November 17, 2016: FEBS Letters
https://www.readbyqxmd.com/read/27859050/capsular-polysaccharide-production-and-serum-survival-of-vibrio-vulnificus-are-dependent-on-antitermination-control-by-rfah
#16
LETTER
Shana B Garrett, Katherine L Garrison-Schilling, Jeffrey T Cooke, Gregg S Pettis
The human pathogen Vibrio vulnificus undergoes phase variation among colonial morphotypes, including a virulent opaque form which produces capsular polysaccharide (CPS) and a translucent phenotype that produces little or no CPS and is attenuated. Here, we found that a V. vulnificus mutant defective for RfaH antitermination control showed a diminished capacity to undergo phase variation and displayed significantly reduced distal gene expression within the Group I CPS operon. Moreover, the rfaH mutant produced negligible CPS and was highly sensitive to killing by normal human serum, results which indicate that RfaH is likely essential for virulence in this bacterium...
November 17, 2016: FEBS Letters
https://www.readbyqxmd.com/read/27861796/oligomeric-status-of-human-cystathionine-beta-synthase-modulates-adomet-binding
#17
LETTER
Angel L Pey, Luis Alfonso Martínez-Cruz, Jan P Kraus, Tomas Majtan
Cystathionine beta-synthase (CBS) plays a key role in the metabolism of sulfur-containing amino acids. CBS is a multidomain tetrameric enzyme allosterically activated by S-adenosylmethionine (AdoMet). Recent crystallographic analyses of engineered CBS lacking the loop made up of residues 516-525 revealed discrepancies in AdoMet binding compared to previous biophysical studies on a full-length CBS. Here, we show that removal of the loop 516-525 functionally eliminates the high affinity sites responsible for kinetic stabilization of the full-length enzyme and yields a dimeric AdoMet-inducible enzyme, in which kinetic stabilization is now exerted by AdoMet binding to the remaining low affinity sites...
November 14, 2016: FEBS Letters
https://www.readbyqxmd.com/read/27861794/evidence-for-dual-receptor-binding-sites-in-clostridium-difficile-toxin-a
#18
LETTER
Gregory S Lambert, Michael R Baldwin
TcdA (308 kDa) and TcdB (270 kDa) disrupt the integrity of the intestinal epithelial barrier and provide an environment favorable for Clostridium difficile colonization. Recent evidence suggests that entry of TcdA into cells is mediated by at least two domains. Here, we report the characterization of a second receptor-binding domain (RBD2) for TcdA. While both the isolated combined repetitive oligopeptides (CROPs) and RBD2 fragments are rapidly internalized into cells under physiologic conditions, only the CROPs domain appreciably accumulates at the cell surface...
November 12, 2016: FEBS Letters
https://www.readbyqxmd.com/read/27861811/the-helical-propensity-of-the-extracellular-loop-is-responsible-for-the-substrate-specificity-of-fe-iii-phytosiderophore-transporters
#19
LETTER
Erisa Harada, Kenji Sugase, Kosuke Namba, Yoshiko Murata
HvYS1 is a selective transporter of Fe(III)-phytosiderophores in barley that is responsible for iron acquisition from the soil. In contrast, maize ZmYS1 possesses broad substrate specificity. In this study, a quantitative evaluation of the transport activities of HvYS1 and ZmYS1 chimera proteins revealed that the seventh extracellular membrane loop is essential for substrate specificity. The loop peptides of both transporters were prepared and analysed by circular dichroism and NMR. The spectra revealed a higher propensity for α-helical conformation of the HvYS1 loop peptide and a largely disordered structure for that of ZmYS1...
November 11, 2016: FEBS Letters
https://www.readbyqxmd.com/read/27861798/characterizing-polyubiquitinated-forms-of-the-neurodegenerative-ubiquitin-mutant-ubb-1
#20
LETTER
Michal Chojnacki, Daoning Zhang, Monika Talarowska, Piotr Gałecki, Janusz Szemraj, David Fushman, Mark A Nakasone
The ubiquitin mutant UBB(+1) has been identified as a hallmark of neurodegenerative disease. In this study, we characterize polyubiquitinated forms of UBB(+1) in vitro and from patient samples. The ability of UBB(+1) to be readily ubiquitinated by several E2 enzymes provided a mechanism for the controlled synthesis and purification of defined conjugates. This allowed us to utilize polyUb-UBB(+1) conjugates for biochemical assays, as well as solution NMR. Coupled with our immunoassay for detection of ubiquitinated forms of UBB(+1) in patient blood samples, we gain a clearer picture of the molecular mechanisms underlying neurodegenerative disease...
November 11, 2016: FEBS Letters
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