Type II secretion system in gram negative bacteria.

Tato práce popisuje stavbu a skládání sekrečního systému typu II, jenž se vyskytuje u některých gramnegativních bakterií, jako je například Vibrio cholerae, Pseudomonas aeruginosa, Legionella pneumophila či Klebsiella oxytoca, a transportuje jejich exoproteiny přes vnější membránu. Dále představí hypotetický mechanismus jeho činnosti a také několik důležitých substrátů, které jsou tímto systémem transportovány - toxiny, enzymy k zisku živin a proteiny účastnící se bakteriálního metabolismu nebo pohybu. Na závěr se věnuje objevu tohoto sekrečního systému v mitochondriích některých protistů a jeho významu pro výzkum evoluce eukaryotních organismů.This thesis describes the structure and the assembly of the type II secretion system which is found in some gram negative bacteria such as Vibrio cholerae, Pseudomonas aeruginosa, Legionella pneumophila or Klebsiella oxytoca and which transports their exoproteins across the outer membrane. The thesis also presents some important substrates translocated by this system - toxins, enzymes and proteins involved in bacterial metabolism or motility - and hypothetical mechanism of the secretion. Conclusion is focused on the discovery of the secretion system in mitochondria of some protists and its importance for the research of the evolution of eukaryotic organisms.Department of ParasitologyKatedra parazitologiePřírodovědecká fakultaFaculty of Scienc

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

Structure and function of mitochondrial secretin.

Type II secretion system (T2SS) is one of the secretion systems found in gram-negative bacteria that provides transport of some bacterial proteins across the outer membrane. The passage through the membrane is mediated by a pore assembled from subunits called GspD or secretin. Together with three other components of T2SS, GspD was discovered in the genome of several protists including Naegleria gruberi, Andalucia godoyi, Reclinomonas americana, Neovahlkampfia damariscottae or in s species of genus Malawimonas. Previously it was found out that these proteins localize into the mitochondria. If found functional and with analogous topology to the bacterial system, the eukaryotic T2SS would represent unique mitochondrial protein export system. Secretin is essential subunit of T2SS which is not only the passive membrane channel, but also participates in the recognition of the substrate. Therefore, the research of the eukaryotic secretin could bring a valuable knowledge about the function of the mitochondrial T2SS. The experimental part of this thesis tries to characterize the eukaryotic secretin and it focuses on (i) the assembly of the secretin channel, in both, the bacteria and in the artificial membranes, (ii) the interactions of GspD with the other subunits of T2SS and (iii) the mechanism of import..

Type II secretion system in gram negative bacteria.

This thesis describes the structure and the assembly of the type II secretion system which is found in some gram negative bacteria such as Vibrio cholerae, Pseudomonas aeruginosa, Legionella pneumophila or Klebsiella oxytoca and which transports their exoproteins across the outer membrane. The thesis also presents some important substrates translocated by this system - toxins, enzymes and proteins involved in bacterial metabolism or motility - and hypothetical mechanism of the secretion. Conclusion is focused on the discovery of the secretion system in mitochondria of some protists and its importance for the research of the evolution of eukaryotic organisms

Heparinizace cévních náhrad aneb "Kam s ním?"

Naše pracoviště se dlouhodobě zabývá vývojem maloprůměrových cévních náhrad. K výrobě těchto materiálů se využívá technologie jehlového elektrostatického zvlákňování s využitím biodegradabilních polyesterů. Tyto tubulární grafty splňují požadavky na cévní náhrady z hlediska morfologie vláken a mechanických vlastností. Jejich nedostatkem však je vysoká trombogenicita. Tento problém jsme se snažili překonat heparinizací nanovlákenných materiálů, která by měla zabránit vzniku krevních sraženin