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Nyon M.P.,Institute of Structural and Molecular Biology ISMB | Segu L.,Institute of Structural and Molecular Biology ISMB | Cabrita L.D.,Institute of Structural and Molecular Biology ISMB | Cabrita L.D.,University College London | And 19 more authors.
Structure | Year: 2012

In conformational diseases, native protein conformers convert to pathological intermediates that polymerize. Structural characterization of these key intermediates is challenging. They are unstable and minimally populated in dynamic equilibria that may be perturbed by many analytical techniques. We have characterized a forme fruste deficiency variant of α 1- antitrypsin (Lys154Asn) that forms polymers recapitulating the conformer-specific neo-epitope observed in polymers that form in vivo. Lys154Asn α 1-antitrypsin populates an intermediate ensemble along the polymerization pathway at physiological temperatures. Nuclear magnetic resonance spectroscopy was used to report the structural and dynamic changes associated with this. Our data highlight an interaction network likely to regulate conformational change and do not support the recent contention that the disease-relevant intermediate is substantially unfolded. Conformational disease intermediates may best be defined using powerful but minimally perturbing techniques, mild disease mutants, and physiological conditions. © 2012 Elsevier Ltd All rights reserved.

Lo A.W.H.,Structural and Molecular Microbiology | Lo A.W.H.,Vrije Universiteit Brussel | Van de Water K.,Structural and Molecular Microbiology | Van de Water K.,Vrije Universiteit Brussel | And 10 more authors.
Journal of Antimicrobial Chemotherapy | Year: 2014

Objectives: To identify and to characterize small-molecule inhibitors that target the subunit polymerization of the type 1 pilus assembly in uropathogenic Escherichia coli (UPEC). Methods: Using an SDS-PAGE-based assay, in silico pre-filtered small-molecule compounds were screened for specific inhibitory activity against the critical subunit polymerization step of the chaperone-usher pathway during pilus biogenesis. The biological activity of one of the compounds was validated in assays monitoring UPEC type 1 pilus biogenesis, type 1 pilus-dependent biofilm formation and adherence to human bladder epithelial cells. The time dependence of the in vivo inhibitory activity and the overall effect of the compound on UPEC growth were determined. Results: N-(4-chloro-phenyl)-2-{5-[4-(pyrrolidine-1-sulfonyl)-phenyl]-[1,3,4]oxadiazol-2-yl sulfanyl}-acetamide (AL1) inhibited in vitro pilus subunit polymerization. In bacterial cultures, AL1 disrupted UPEC type 1 pilus biogenesis and pilus-dependent biofilm formation, and resulted in the reduction of bacterial adherence to human bladder epithelial cells, without affecting bacterial cell growth. Bacterial exposure to the inhibitor led to an almost instantaneous loss of type 1 pili. Conclusions: We have identified and characterized a small molecule that interferes with the assembly of type 1 pili. The molecule targets the polymerization step during the subunit incorporation cycle of the chaperone-usher pathway. Our discovery provides new insight into the design and development of novel anti-virulence therapies targeting key virulence factors of bacterial pathogens. © The Author 2013. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved.

Ruer S.,Structural Biology Research Center | Pinotsis N.,Institute of Structural and Molecular Biology ISMB | Steadman D.,University College London | Waksman G.,Institute of Structural and Molecular Biology ISMB | And 2 more authors.
Chemical Biology and Drug Design | Year: 2015

In view of the relentless increase in antibiotic resistance in human pathogens, efforts are needed to safeguard our future therapeutic options against infectious diseases. In addition to regulatory changes in our antibiotic use, this will have to include the development of new therapeutic compounds. One area that has received growing attention in recent years is the possibility to treat or prevent infections by targeting the virulence mechanisms that render bacteria pathogenic. Antivirulence targets include bacterial adherence, secretion of toxic effector molecules, bacterial persistence through biofilm formation, quorum sensing and immune evasion. Effective small-molecule compounds have already been identified that suppress such processes. In this review, we discuss the susceptibility of such compounds to the development of resistance, by comparison with known resistance mechanisms observed for classical bacteriostatic or bacteriolytic antibiotics, and by review of available experimental case studies. Unfortunately, appearance of resistance mechanisms has already been demonstrated for some, showing that the quest of new, lasting drugs remains complicated. © 2015 John Wiley & Sons A/S.

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