Import proteinů do mitochondrií a peroxisomů parazitických prvoků

Předkládaná práce vychází ze tří projektů, kterým je společný zájem o evoluci eukaryotických organel a molekulárních systémů importu proteinů. První projekt poukazuje na možnost, že se peroxisomy (typické organely aerobních eukaryot) zachovaly u anaerobní skupiny Archamoebae, která zahrnuje parazita Entamoeba histolytica a volně žijícího prvoka Mastigamoeba balamuthi. Nejsilnějším vodítkem byl nález proteinů homologních ke známým komponentám peroxisomálního importu proteinů. Cílem druhého projektu je charakterizovat neznámou proteinovou translokázu vnitřní membrány mitosomů (redukovaných mitochondrií) u anaerobního prvoka Giardia intestinalis, kde se podařilo objevit podjednotku Tim44 této translokázy. Poslední projekt ukazuje, že translokáza vnější mitochondriální membrány trypanosomatid je příbuzná typické eukaryotické translokáze Tom40. Toto zjištění je důležité, neboť nepřítomnost Tom40 byla dříve považována za jeden z ancestrálních znaků trypanosomatid.The presented thesis includes three related projects, that are linked by a common interest in the evolution of eukaryotic organelles and machineries that import proteins into these compartments. The first project considers the possibility of peroxisomes (eukaryotic organelles known in aerobic organisms) being conserved in two related anaerobic protists: a free-living amoeba Mastigamoeba balamuthi and a parasite Entamoeba histolytica. The most important hint for the presence of peroxisomes was the discovery of proteins that are homologous to known components of the peroxisomal protein import machinery. The second project aims to characterize the unknown protein translocase of the inner membrane (TIM) in the mitosomes (extremely reduced mitochondria) of an anaerobic protozoan Giardia intestinalis. We have discovered an important subunit of the mitosomal translocase (Tim44), which usually tethers the Hsp70/PAM (presequence translocase-associated motor) complex to the TIM translocon. The last project shows that the protein translocase of the outer mitochondrial membrane in trypanosomatids is related to a typical eukaryotic channel Tom40. This finding is important because the absence of Tom40 was previously considered an ancestral feature of trypanosomatids.Department of ParasitologyKatedra parazitologieFaculty of SciencePřírodovědecká fakult

Analysis of diverse eukaryotes suggests the existence of an ancestral mitochondrial apparatus derived from the bacterial type II secretion system

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

Additional file 4: Table S3. of Evolutionary loss of peroxisomes – not limited to parasites

Table of putative peroxisomal enzymes and the prediction of their localization. (XLS 7288 kb

Additional file 4: Table S2. of Evolution of the Tim17 protein family

The overall distribution of Tim17 family protein in eukaryotes. (XLS 135 kb

Additional file 6: Table S4. of Evolution of the Tim17 protein family

Prokaryotic proteins carrying a PRAT motif [(G/A)X2(F/Y)X10RX3DX6(G/A/S)GX3G]. (PDF 133 kb

Additional file 3: Figure S1. of Evolutionary loss of peroxisomes – not limited to parasites

Phylogeny of Pex10 and other zinc-finger domain containing proteins showing, that O. dioica GSOIDT00013970001 sequence isn't monophyletic with eukaryotic Pex10 sequences. Bootsrap supports are shown. (PDF 351 kb

Additional file 2: Table S2. of Evolutionary loss of peroxisomes – not limited to parasites

Table of peroxins identified. (XLS 677 kb