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1.
Nat Commun ; 12(1): 2947, 2021 05 19.
Artigo em Inglês | MEDLINE | ID: mdl-34011950

RESUMO

The type 2 secretion system (T2SS) is present in some Gram-negative eubacteria and used to secrete proteins across the outer membrane. Here we report that certain representative heteroloboseans, jakobids, malawimonads and hemimastigotes unexpectedly possess homologues of core T2SS components. We show that at least some of them are present in mitochondria, and their behaviour in biochemical assays is consistent with the presence of a mitochondrial T2SS-derived system (miT2SS). We additionally identified 23 protein families co-occurring with miT2SS in eukaryotes. Seven of these proteins could be directly linked to the core miT2SS by functional data and/or sequence features, whereas others may represent different parts of a broader functional pathway, possibly also involving the peroxisome. Its distribution in eukaryotes and phylogenetic evidence together indicate that the miT2SS-centred pathway is an ancestral eukaryotic trait. Our findings thus have direct implications for the functional properties of the early mitochondrion.


Assuntos
Evolução Molecular , Mitocôndrias/genética , Mitocôndrias/metabolismo , Sistemas de Secreção Tipo II/genética , Sistemas de Secreção Tipo II/metabolismo , Sequência de Aminoácidos , Sequência Conservada , Eucariotos/classificação , Eucariotos/genética , Eucariotos/metabolismo , Bactérias Gram-Negativas/classificação , Bactérias Gram-Negativas/genética , Bactérias Gram-Negativas/metabolismo , Proteínas Mitocondriais/classificação , Proteínas Mitocondriais/genética , Proteínas Mitocondriais/metabolismo , Modelos Biológicos , Modelos Moleculares , Naegleria/classificação , Naegleria/genética , Naegleria/metabolismo , Peroxissomos/metabolismo , Filogenia , Proteínas de Protozoários/classificação , Proteínas de Protozoários/genética , Proteínas de Protozoários/metabolismo , Homologia de Sequência de Aminoácidos , Sistemas de Secreção Tipo II/classificação
2.
Biochim Biophys Acta Biomembr ; 1862(10): 183405, 2020 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-32593615

RESUMO

Surfactin, a cyclic lipoheptapeptide produced by Bacillus subtilis, is a surface-active antimicrobial that targets the barrier function of lipid membranes. It inserts itself into the membrane, where it forms conductive pores. Depending on its concentration, it eventually disintegrates the membrane in a detergent-like manner. The molecular details of this activity are not yet sufficiently understood, nor are the mechanisms that the surfactin producer employs to resist its own toxic product. We have previously shown that B. subtilis modifies its membrane lipid composition upon the onset of surfactin production, mainly increasing the cardiolipin content. Here we show that the increased cardiolipin content leads to a decreased surfactin-induced leakage of liposomes reconstituted from lipids isolated from the surfactin producer. This stabilizing effect of cardiolipin is concentration-dependent. Using a propidium iodide-based cell permeabilization assay, we further confirmed that the cytoplasmic membrane of the mutant B. subtilis strain lacking cardiolipin was substantially more susceptible to the action of surfactin, even though the amount of bound surfactin was the same as in the wild-type strain. We propose that membrane remodelling; due to the increase in cardiolipin content, contributes to the surfactin tolerance of B. subtilis.


Assuntos
Bacillus subtilis/metabolismo , Cardiolipinas/metabolismo , Permeabilidade da Membrana Celular , Lipopeptídeos/metabolismo , Peptídeos Cíclicos/metabolismo , Membrana Celular/metabolismo , Lipossomos
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