Suchergebnisse

23 p.-7 fig. ; The intermediate filament protein vimentin is involved in essential cellular processes, including cell division and stress responses, as well as in the pathophysiology of cancer, pathogen infection, and autoimmunity. The vimentin network undergoes marked reorganizations in response to oxidative stress, in which modifications of vimentin single cysteine residue, Cys328, play an important role, and is modulated by zinc availability. However, the molecular basis for this regulation is not fully understood. Here, we show that Cys328 displays a low pKa, supporting its reactivity, and is readily alkylated and oxidized in vitro. Moreover, combined oxidation and crosslinking assays and molecular dynamics simulations support that zinc ions interact with Cys328 in its thiolate form, whereas Glu329 and Asp331 stabilize zinc coordination. Vimentin oxidation can induce disulfide crosslinking, implying the close proximity of Cys328 from neighboring dimers in certain vimentin conformations, supported by our computational models. Notably, micromolar zinc concentrations prevent Cys328 alkylation, lipoxidation, and disulfide formation. Moreover, zinc selectively protects vimentin from crosslinking using short-spacer cysteine-reactive but not amine-reactive agents. These effects are not mimicked by magnesium, consistent with a lower number of magnesium ions hosted at the cysteine region, according to molecular dynamics simulations. Importantly, the region surrounding Cys328 is involved in interaction with several drugs targeting vimentin and is conserved in type III intermediate filaments, which include glial fibrillary acidic protein and desmin. Altogether, our results identify this region as a hot spot for zinc binding, which modulates Cys328 reactivity. Moreover, they provide a molecular standpoint for vimentin regulation through the interplay between cysteine modifications and zinc availability. ; This work was supported by the European Union's Horizon 2020 research and innovation program under the Marie Sklodowska-Curie Grant Agreement No. 675132 "Masstrplan", Grants SAF2015-68590-R and RTI2018-097624-B-I00 from Agencia Estatal de Investigación, MICINN/FEDER, Spain, and Instituto de Salud Carlos III/FEDER, RETIC ARADyAL RD16/0006/0021 to DPS; Grant CTQ2017-88353-R from MICINN to SMS; Grant BES-2015-071588 from MICINN to JGC. ; Peer reviewed

19 p.-6 fig.-2 tab. ; The increase of infections caused by multidrug-resistant bacteria, together with the loss of effectiveness of currently available antibiotics, represents one of the most serious threats to public health worldwide. The loss of human lives and the economic costs associated to the problem of the dissemination of antibiotic resistance require immediate action. Bacteria, known by their great genetic plasticity, are capable not only of mutating their genes to adapt to disturbances and environmental changes but also of acquiring new genes that allow them to survive in hostile environments, such as in the presence of antibiotics. One of the major mechanisms responsible for the horizontal acquisition of new genes (e.g., antibiotic resistance genes) is bacterial conjugation, a process mediated by mobile genetic elements such as conjugative plasmids and integrative conjugative elements. Conjugative plasmids harboring antibiotic resistance genes can be transferred from a donor to a recipient bacterium in a process that requires physical contact. After conjugation, the recipient bacterium not only harbors the antibiotic resistance genes but it can also transfer the acquired plasmid to other bacteria, thus contributing to the spread of antibiotic resistance. Conjugative plasmids have genes that encode all the proteins necessary for the conjugation to take place, such as the type IV coupling proteins (T4CPs) present in all conjugative plasmids. Type VI coupling proteins constitute a heterogeneous family of hexameric ATPases that use energy from the ATP hydrolysis for plasmid transfer. Taking into account their essential role in bacterial conjugation, T4CPs are attractive targets for the inhibition of bacterial conjugation and, concomitantly, the limitation of antibiotic resistance dissemination. This review aims to compile present knowledge on T4CPs as a starting point for delving into their molecular structure and functioning in future studies. Likewise, the scientific literature on bacterial conjugation inhibitors has been reviewed here, in an attempt to elucidate the possibility of designing T4CP-inhibitors as a potential solution to the dissemination of multidrug-resistant bacteria. ; This work has been supported by the University of the Basque Country (GIU18/229 and COLAB19/08), the Department of Economic Development and Infrastructures of the Basque Government (ELKARTEK 2020 KK-2020/00007), and the Spanish Ministry of Science and Innovation (CTQ2017-88353-R and PID2019-110055RB-C21). ; Peer reviewed

12 p.-7 fig.-1 schem.-1 graph. abst. ; Modern adjuvants for vaccine formulations are immunostimulating agents whose action is based on the activation of pattern recognition receptors (PRRs) by well-defined ligands to boost innate and adaptive immune responses. Monophosphoryl lipid A (MPLA), a detoxified analogue of lipid A, is a clinically approved adjuvant that stimulates toll-like receptor 4 (TLR4). The synthesis of MPLA poses manufacturing and quality assessment challenges. Bridging this gap, we report here the development and preclinical testing of chemically simplified TLR4 agonists that could sustainably be produced in high purity and on a large scale. Underpinned by computational and biological experiments, we show that synthetic monosaccharide-based molecules (FP compounds) bind to the TLR4/MD-2 dimer with submicromolar affinities stabilizing the active receptor conformation. This results in the activation of MyD88- and TRIF-dependent TLR4 signaling and the NLRP3 inflammasome. FP compounds lack in vivo toxicity and exhibit adjuvant activity by stimulating antibody responses with a potency comparable to MPLA. ; The support from European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 860325 (www.BactiVax.eu), Italian Ministry grant PRIN 2017, no. 2017E44A9P (BacHounds:Supramolecular nanostructures for bacteria detection), and the Spanish Ministry for Science and Innovation (grants CTQ2017-88353-R and PRE2018-086249) is acknowledged. ; Peer reviewed

16 p.-9 fig.-1 tab. ; The cardiovascular toxicity of Abacavir is related to its purinergic structure. Purinergic P2X7-receptors (P2X7R), characterized by activation by high concentrations of ATP and with high plasticity, seem implicated. We appraise the nature of the interplay between Abacavir and P2X7R in generating vascular inflammation. The effects of Abacavir on leukocyte-endothelium interactions were compared with those of its metabolite carbovir triphosphate (CBV-TP) or ATP in the presence of apyrase (ATP-ase) or A804598 (P2X7R-antagonist). CBV-TP and ATP levels were evaluated by HPLC, while binding of Abacavir, CBV-TP and ATP to P2X7R was assessed by radioligand and docking studies. Hypersensitivity studies explored a potential allosteric action of Abacavir. Clinical concentrations of Abacavir (20 µmol/L) induced leukocyte-endothelial cell interactions by specifically activating P2X7R, but the drug did not show affinity for the P2X7R ATP-binding site (site 1). CBV-TP levels were undetectable in Abacavir-treated cells, while those of ATP were unaltered. The effects of Abacavir were Apyrase-dependent, implying dependence on endogenous ATP. Exogenous ATP induced a profile of proinflammatory actions similar to Abacavir, but was not entirely P2X7R-dependent. Docking calculations suggested ATP-binding to sites 1 and 2, and Abacavir-binding only to allosteric site 2. A combination of concentrations of Abacavir (1 µmol/L) and ATP (0.1 µmol/L) that had no effect when administered separately induced leukocyte-endothelium interactions mediated by P2X7R and involving Connexin43 channels. Therefore, Abacavir acts as a positive allosteric modulator of P2X7R, turning low concentrations of endogenous ATP themselves incapable of stimulating P2X7R into a functional proinflammatory agonist of the receptor. ; This work was supported by Ministerio de Economía y Competitividad and the European Regional Development fund of the European Union (FEDER) (SAF2015–67678-R, RTI2018-094436-B-I00 and CTQ2017-88353-R), Ministerio de Sanidad y Consumo (CB06/04/0071, CIBERehd) and Generalitat Valenciana (PROMETEOII/2014/035 and PROMETEO 2018/141), along with an unrestricted grant from GILEAD S.L. VCD and ASL were funded by VALI + D program from Generalitat Valenciana (grants number ACIF/2015/316 and ACIF/2016/119, respectively) and PGM by FPU program from Ministerio de Educación, Cultura y Deporte (grant number FPU16/06064) and MABR by FPU program from Ministerio de Ciencia, Innovación y Universidades (grant number FPU17/04249). ; Peer reviewed

29 p.-6 fig.-2 tab.-7 fig. supl.-2 tab. supl.-1 graph. abst. ; Siglec-10 is an inhibitory I-type lectin selectively recognizing sialoglycans exposed on cell surfaces, involved in several patho-physiological processes. The key role Siglec-10 plays in the regulation of immune cell functions has made it a potential target for the development of immunotherapeutics against a broad range of diseases. However, the crystal structure of the protein has not been resolved for the time being and the atomic description of Siglec-10 interactions with complex glycans has not been previously unraveled. We present here the first insights of the molecular mechanisms regulating the interaction between Siglec-10 and naturally occurring sialoglycans. We used combined spectroscopic, computational and biophysical approaches to dissect glycans' epitope mapping and conformation upon binding in order to afford a description of the 3D complexes. Our outcomes provide a structural perspective for the rational design and development of high-affinity ligands to control the receptor functionality. ; This study was supported by the project ''GLYTUNES'' funded by MIUR Progetti di Ricerca di Rilevante Interesse Nazionale (PRIN 2017) (2017XZ2ZBK, 2019–2022) to A.S.; by progetto POR SATIN and Progetto POR CampaniaOncoterapia to A.M.; by the European Commission (H2020-MSCA- 814102-SWEET CROSSTALK project) to A.M., R.M., and A.S. This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program under grant agreement No 851356 to R.M. FSE,PON Ricerca e Innovazione 2014–2020, Azione I.1 ''Dottorati Innovativi con caratterizzazione Industriale'' is acknowledged for funding the PhD grant to R.E.F. Grants by the Spanish Ministry of Science MICINN (CTQ2017-88353-R and fellowship BES 2015–071588 to J.G.-C.) and Wellcome Trust 103744/Z/14/Z to P.R.C. are acknowledged. ; Peer reviewed

23 p.-9 fig.-4 tab. ; Tracking bacterial evolution during chronic infection provides insights into how host selection pressures shape bacterial genomes. The human-restricted opportunistic pathogen nontypeable Haemophilus influenzae (NTHi) infects the lower airways of patients suffering chronic obstructive pulmonary disease (COPD) and contributes to disease progression. To identify bacterial genetic variation associated with bacterial adaptation to the COPD lung, we sequenced the genomes of 92 isolates collected from the sputum of 13 COPD patients over 1 to 9years. Individuals were colonized by distinct clonal types (CTs) over time, but the same CT was often reisolated at a later time or found in different patients. Although genomes from the same CT were nearly identical, intra-CT variation due to mutation and recombination occurred. Recurrent mutations in several genes were likely involved in COPD lung adaptation. Notably, nearly a third of CTs were polymorphic for null alleles of ompP1 (also called fadL), which encodes a bifunctional membrane protein that both binds the human carcinoembryonic antigen-related cell adhesion molecule 1 (hCEACAM1) receptor and imports long-chain fatty acids (LCFAs). Our computational studies provide plausible three-dimensional models for FadL's interaction with hCEACAM1 and LCFA binding. We show that recurrent fadL mutations are likely a case of antagonistic pleiotropy, since loss of FadL reduces NTHi's ability to infect epithelia but also increases its resistance to bactericidal LCFAs enriched within the COPD lung. Supporting this interpretation, truncated fadL alleles are common in publicly available NTHi genomes isolated from the lower airway tract but rare in others. These results shed light on molecular mechanisms of bacterial pathoadaptation and guide future research toward developing novel COPD therapeutics.IMPORTANCE Nontypeable Haemophilus influenzae is an important pathogen in patients with chronic obstructive pulmonary disease (COPD). To elucidate the bacterial pathways undergoing in vivo evolutionary adaptation, we compared bacterial genomes collected over time from 13 COPD patients and identified recurrent genetic changes arising in independent bacterial lineages colonizing different patients. Besides finding changes in phase-variable genes, we found recurrent loss-of-function mutations in the ompP1 (fadL) gene. We show that loss of OmpP1/FadL function reduces this bacterium's ability to infect cells via the hCEACAM1 epithelial receptor but also increases its resistance to bactericidal fatty acids enriched within the COPD lung, suggesting a case of antagonistic pleiotropy that restricts DeltafadL strains' niche. These results show how H. influenzae adapts to host-generated inflammatory mediators in the COPD airways. ; This work has been funded by MINECO grants SAF2012-31166 and SAF2015-66520-R to J.G. and grants CTQ2014-57141-R and CTQ2017-88353-R to S.M.-S.; grant 03/2016 from the Health Department, Regional Government of Navarra, Spain, and SEPAR grant 31/2015 to J.G.; and NIDCD grant 5R01 DC 02148 and NIDDK grant 1U01 DK082316 from the U.S. National Institutes of Health to G.D.E. CIBERES is an initiative from the Instituto de Salud Carlos III (ISCIII), Madrid, Spain. J.M. and L.P.-R. were funded by Ph.D.studentships BES-2013-062644 and BES-2012-053653 from MINECO, Spain. ; Peer reviewed

Tracking bacterial evolution during chronic infection provides insights into how host selection pressures shape bacterial genomes. The human-restricted opportunistic pathogen nontypeable Haemophilus influenzae (NTHi) infects the lower airways of patients suffering chronic obstructive pulmonary disease (COPD) and contributes to disease progression. To identify bacterial genetic variation associated with bacterial adaptation to the COPD lung, we sequenced the genomes of 92 isolates collected from the sputum of 13 COPD patients over 1 to 9 years. Individuals were colonized by distinct clonal types (CTs) over time, but the same CT was often reisolated at a later time or found in different patients. Although genomes from the same CT were nearly identical, intra-CT variation due to mutation and recombination occurred. Recurrent mutations in several genes were likely involved in COPD lung adaptation. Notably, nearly a third of CTs were polymorphic for null alleles of ompP1 (also called fadL), which encodes a bifunctional membrane protein that both binds the human carcinoembryonic antigen-related cell adhesion molecule 1 (hCEACAM1) receptor and imports long-chain fatty acids (LCFAs). Our computational studies provide plausible three-dimensional models for FadL's interaction with hCEACAM1 and LCFA binding. We show that recurrent fadL mutations are likely a case of antagonistic pleiotropy, since loss of FadL reduces NTHi's ability to infect epithelia but also increases its resistance to bactericidal LCFAs enriched within the COPD lung. Supporting this interpretation, truncated fadL alleles are common in publicly available NTHi genomes isolated from the lower airway tract but rare in others. These results shed light on molecular mechanisms of bacterial pathoadaptation and guide future research toward developing novel COPD therapeutics. IMPORTANCE Nontypeable Haemophilus influenzae is an important pathogen in patients with chronic obstructive pulmonary disease (COPD). To elucidate the bacterial pathways undergoing in vivo evolutionary adaptation, we compared bacterial genomes collected over time from 13 COPD patients and identified recurrent genetic changes arising in independent bacterial lineages colonizing different patients. Besides finding changes in phase-variable genes, we found recurrent loss-of-function mutations in the ompP1 (fadL) gene. We show that loss of OmpP1/FadL function reduces this bacterium's ability to infect cells via the hCEACAM1 epithelial receptor but also increases its resistance to bactericidal fatty acids enriched within the COPD lung, suggesting a case of antagonistic pleiotropy that restricts ΔfadL strains' niche. These results show how H. influenzae adapts to host-generated inflammatory mediators in the COPD airways. ; This work has been funded by MINECO grants SAF2012-31166 and SAF2015-66520-R to J.G. and grants CTQ2014-57141-R and CTQ2017-88353-R to S.M.-S.; grant 03/2016 from the Health Department, Regional Government of Navarra, Spain, and SEPAR grant 31/2015 to J.G.; and NIDCD grant 5R01 DC 02148 and NIDDK grant 1U01 DK082316 from the U.S. National Institutes of Health to G.D.E. CIBERES is an initiative from the Instituto de Salud Carlos III (ISCIII), Madrid, Spain. J.M. and L.P.-R. were funded by Ph.D. studentships BES-2013-062644 and BES-2012-053653 from MINECO, Spain. A.F.-C. was funded by a contract from MINECO, reference number 20132RC947. I.R.-A. was funded by a Ph.D. studentship from the Universidad Pública de Navarra, Spain. S.M. is funded by a postdoctoral contract from CIBERES.