Browsing by Subject "MEMBRANE PERMEABILIZATION"

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  • Domanska, Ausra; Guryanov, Sergey; Butcher, Sarah J. (2021)
    Parechoviruses belong to the genus Parechovirus within the family Picornaviridae and are non-enveloped icosahedral viruses with a single-stranded RNA genome. Parechoviruses include human and animal pathogens classified into six species. Those that infect humans belong to the Parechovirus A species and can cause infections ranging from mild gastrointestinal or respiratory illness to severe neonatal sepsis. There are no approved antivirals available to treat parechovirus (nor any other picornavirus) infections. In this parechovirus review, we focus on the cleaved protein products resulting from the polyprotein processing after translation comparing and contrasting their known or predicted structures and functions to those of other picornaviruses. The review also includes our original analysis from sequence and structure prediction. This review highlights significant structural differences between parechoviral and other picornaviral proteins, suggesting that parechovirus drug development should specifically be directed to parechoviral targets.
  • Fewer, David P.; Jokela, Jouni; Heinila, Lassi; Aesoy, Reidun; Sivonen, Kaarina; Galica, Tomas; Hrouzek, Pavel; Herfindal, Lars (2021)
    Cyanobacteria produce a variety of chemically diverse cyclic lipopeptides with potent antifungal activities. These cyclic lipopeptides have an amphipathic structure comprised of a polar peptide cycle and hydrophobic fatty acid side chain. Many have antibiotic activity against a range of human and plant fungal pathogens. This review article aims to summarize the present knowledge on the chemical diversity and cellular effects of cyanobacterial cyclic lipopeptides that display antifungal activity. Cyclic antifungal lipopeptides from cyanobacteria commonly fall into four structural classes; hassallidins, puwainaphycins, laxaphycins, and anabaenolysins. Many of these antifungal cyclic lipopeptides act through cholesterol and ergosterol-dependent disruption of membranes. In many cases, the cyclic lipopeptides also exert cytotoxicity in human cells, and a more extensive examination of their biological activity and structure-activity relationship is warranted. The hassallidin, puwainaphycin, laxaphycin, and anabaenolysin structural classes are unified through shared complex biosynthetic pathways that encode a variety of unusual lipoinitiation mechanisms and branched biosynthesis that promote their chemical diversity. However, the biosynthetic origins of some cyanobacterial cyclic lipopeptides and the mechanisms, which drive their structural diversification in general, remain poorly understood. The strong functional convergence of differently organized chemical structures suggests that the production of lipopeptide confers benefits for their producer. Whether these benefits originate from their antifungal activity or some other physiological function remains to be answered in the future. However, it is clear that cyanobacteria encode a wealth of new cyclic lipopeptides with novel biotechnological and therapeutic applications.
  • Pihan, Philippe; Lisbona, Fernanda; Borgonovo, Janina; Edwards-Jorquera, Sandra; Nunes-Hasler, Paula; Castillo, Karen; Kepp, Oliver; Urra, Hery; Saarnio, Suvi; Vihinen, Helena; Carreras-Sureda, Amado; Forveille, Sabrina; Sauvat, Allan; De Giorgis, Daniela; Pupo, Amaury; Rodriguez, Diego A.; Quarato, Giovanni; Sagredo, Alfredo; Lourido, Fernanda; Letai, Anthony; Latorre, Ramon; Kroemer, Guido; Demaurex, Nicolas; Jokitalo, Eija; Concha, Miguel L.; Glavic, Alvaro; Green, Douglas R.; Hetz, Claudio (2021)
    Programmed cell death is regulated by the balance between activating and inhibitory signals. Here, we have identified RECS1 (responsive to centrifugal force and shear stress 1) [also known as TMBIM1 (transmembrane BAX inhibitor motif containing 1)] as a proapoptotic member of the TMBIM family. In contrast to other proteins of the TMBIM family, RECS1 expression induces cell death through the canonical mitochondrial apoptosis pathway. Unbiased screening indicated that RECS1 sensitizes cells to lysosomal perturbations. RECS1 localizes to lysosomes, where it regulates their acidification and calcium content, triggering lysosomal membrane permeabilization. Structural modeling and electrophysiological studies indicated that RECS1 is a pH-regulated calcium channel, an activity that is essential to trigger cell death. RECS1 also sensitizes whole animals to stress in vivo in Drosophila melanogaster and zebrafish models. Our results unveil an unanticipated function for RECS1 as a proapoptotic component of the TMBIM family that ignites cell death programs at lysosomes.
  • Hajek, Jan; Bieringer, Sebastian; Voracova, Katerina; Macho, Marketa; Saurav, Kumar; Delawska, Katerina; Divoka, Petra; Fiser, Radovan; Mikusova, Gabriela; Cheel, Jose; Fewer, David P.; Vu, Dai Long; Paichlova, Jindriska; Riepl, Herbert; Hrouzek, Pavel (2021)
    Microbial cyclic lipopeptides are an important class of antifungal compounds with applications in pharmacology and biotechnology. However, the cytotoxicity of many cyclic lipopeptides limits their potential as antifungal drugs. Here we present a structure-activity relationship study on the puwainaphycin/minutissamide (PUW/MIN) family of cyclic lipopeptides isolated from cyanobacteria. PUWs/MINs with variable fatty acid chain lengths differed in the dynamic of their cytotoxic effect despite their similar IC50 after 48 hours (2.8 mu M for MIN A and 3.2 mu M for PUW F). Furthermore, they exhibited different antifungal potency with the lowest MIC values obtained for MIN A and PUW F against the facultative human pathogen Aspergillus fumigatus (37 mu M) and the plant pathogen Alternaria alternata (0.6 mu M), respectively. We used a Grignard-reaction with alkylmagnesium halides to lengthen the lipopeptide FA moiety as well as the Steglich esterification on the free hydroxyl substituents to prepare semi-synthetic lipopeptide variants possessing multiple fatty acid tails. Cyclic lipopeptides with extended and branched FA tails showed improved strain-specific antifungal activity against A. fumigatus (MIC = 0.5-3.8 mu M) and A. alternata (MIC = 0.1-0.5 mu M), but with partial retention of the cytotoxic effect (similar to 10-20 mu M). However, lipopeptides with esterified free hydroxyl groups possessed substantially higher antifungal potencies, especially against A. alternata (MIC = 0.2-0.6 mu M), and greatly reduced or abolished cytotoxic activity (>20 mu M). Our findings pave the way for a generation of semi-synthetic variants of lipopeptides with improved and selective antifungal activities.
  • Korotkov, Sergey M.; Konovalova, Svetlana A.; Brailovskaya, Irina V.; Saris, Nils-Erik L. (2016)
    The conformation of adenine nucleotide translocase (ANT) has a profound impact in opening the mitochondrial permeability transition pore (MPTP) in the inner membrane. Fixing the ANT in 'c' conformation by phenylarsine oxide (PAO), tert-butylhydroperoxide (tBHP), and carboxyatractyloside as well as the interaction of 4,4'-diisothiocyanostilbene-2,2'-disulfonate (DIDS) with mitochondrial thiols markedly attenuated the ability of ADP to inhibit the MPTP opening. We earlier found (Korotkov and Saris, 2011) that calcium load of rat liver mitochondria in medium containing TINO3 and KNO3 stimulated the Tl+-induced MPTP opening in the inner mitochondrial membrane. The MPTP opening as well as followed increase in swelling, a drop in membrane potential (Delta Psi(mito)), and a decrease in state 3, state 4, and 2,4-dinitrophenol-uncoupled respiration were visibly enhanced in the presence of PAO, tBHP, DIDS, and carboxyatractyloside. However, these effects were markedly inhibited by ADP and membrane-penetrant hydrophobic thiol reagent, N-ethylmaleimide (NEM) which fix the ANT in 'm' conformation. Cyclosporine A additionally potentiated these effects of ADP and NEM. Our data suggest that conformational changes of the ANT may be directly involved in the opening of the Tl+-induced MPTP in the inner membrane of Ca2+-loaded rat liver mitochondria. Using the Tl+-induced MPTP model is discussed in terms finding new transition pore inhibitors and inducers among different chemical and natural compounds. (C) 2016 Elsevier Ltd. All rights reserved.