RESUMO
Trypanosoma brucei is an important human pathogen. In this study, we have focused on the characterization of FtsH protease, ATP-dependent membrane-bound mitochondrial enzyme important for regulation of protein abundance. We have determined localization and orientation of all six putative T.brucei FtsH homologs in the inner mitochondrial membrane by in silico analyses, by immunofluorescence, and with protease assay. The evolutionary origin of these homologs has been tested by comparative phylogenetic analysis. Surprisingly, some kinetoplastid FtsH proteins display inverted orientation in the mitochondrial membrane compared to related proteins of other examined eukaryotes. Moreover, our data strongly suggest that during evolution the orientation of FtsH protease in T. brucei varied due to both loss and acquisition of the transmembrane domain.
Assuntos
Evolução Molecular , Proteínas Mitocondriais/química , Peptídeo Hidrolases/química , Proteínas de Protozoários/química , Trypanosoma brucei brucei/enzimologia , Animais , Arabidopsis/classificação , Arabidopsis/enzimologia , Arabidopsis/genética , Sequência Conservada , Euglena gracilis/classificação , Euglena gracilis/enzimologia , Euglena gracilis/genética , Euglena longa/classificação , Euglena longa/enzimologia , Euglena longa/genética , Expressão Gênica , Humanos , Isoenzimas/química , Isoenzimas/genética , Isoenzimas/metabolismo , Leishmania major/classificação , Leishmania major/enzimologia , Leishmania major/genética , Camundongos , Mitocôndrias/enzimologia , Mitocôndrias/genética , Membranas Mitocondriais/química , Membranas Mitocondriais/enzimologia , Proteínas Mitocondriais/genética , Proteínas Mitocondriais/metabolismo , Peptídeo Hidrolases/genética , Peptídeo Hidrolases/metabolismo , Filogenia , Domínios Proteicos , Proteínas de Protozoários/genética , Proteínas de Protozoários/metabolismo , Saccharomyces cerevisiae/classificação , Saccharomyces cerevisiae/enzimologia , Saccharomyces cerevisiae/genética , Trypanosoma brucei brucei/classificação , Trypanosoma brucei brucei/genéticaRESUMO
Euglenophytes are a familiar algal group with green alga-derived secondary plastids, but the knowledge of euglenophyte plastid function and evolution is still highly incomplete. With this in mind we sequenced and analysed the transcriptome of the non-photosynthetic species Euglena longa. The transcriptomic data confirmed the absence of genes for the photosynthetic machinery, but provided candidate plastid-localised proteins bearing N-terminal bipartite topogenic signals (BTSs) of the characteristic euglenophyte type. Further comparative analyses including transcriptome assemblies available for photosynthetic euglenophytes enabled us to unveil salient aspects of the basic euglenophyte plastid infrastructure, such as plastidial targeting of several proteins as C-terminal translational fusions with other BTS-bearing proteins or replacement of the conventional eubacteria-derived plastidial ribosomal protein L24 by homologs of archaeo-eukaryotic origin. Strikingly, no homologs of any key component of the TOC/TIC system and the plastid division apparatus are discernible in euglenophytes, and the machinery for intraplastidial protein targeting has been simplified by the loss of the cpSRP/cpFtsY system and the SEC2 translocon. Lastly, euglenophytes proved to encode a plastid-targeted homolog of the termination factor Rho horizontally acquired from a Lambdaproteobacteria-related donor. Our study thus further documents a substantial remodelling of the euglenophyte plastid compared to its green algal progenitor.
