Ellen L. Zechner

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Type IV secretion occurs across a wide range of prokaryotic cell envelopes: Gram-negative, Gram-positive, cell wall-less bacteria and some archaea. This diversity is reflected in the heterogeneity of components that constitute the secretion machines. Macromolecules are secreted in an ATP-dependent process using an envelope-spanning multi-protein channel.(More)
TraG-like proteins are potential NTP hydrolases (NTPases) that are essential for DNA transfer in bacterial conjugation. They are thought to mediate interactions between the DNA-processing (Dtr) and the mating pair formation (Mpf) systems. TraG-like proteins also function as essential components of type IV secretion systems of several bacterial pathogens(More)
Campylobacter fetus are important animal and human pathogens and the two major subspecies differ strikingly in pathogenicity. C. fetus subsp. venerealis is highly niche-adapted, mainly infecting the genital tract of cattle. C. fetus subsp. fetus has a wider host-range, colonizing the genital- and intestinal-tract of animals and humans. We report the(More)
Bacterial conjugation is a form of type IV secretion that transports protein and DNA to recipient cells. Specific bacteriophage exploit the conjugative pili and cell envelope spanning protein machinery of these systems to invade bacterial cells. Infection by phage R17 requires F-like pili and coupling protein TraD, which gates the cytoplasmic entrance of(More)
Relaxases are proteins responsible for the transfer of plasmid and chromosomal DNA from one bacterium to another during conjugation. They covalently react with a specific phosphodiester bond within DNA origin of transfer sequences, forming a nucleo-protein complex which is subsequently recruited for transport by a plasmid-encoded type IV secretion system.(More)
Most natural conjugative IncF plasmids encode a fertility inhibition system that represses transfer gene expression in the majority of plasmid-carrying cells. The successful spread of these plasmids in clinically relevant bacteria has been suggested to be supported by a transitory derepression of transfer gene expression in newly formed transconjugants. In(More)
Campylobacter fetus infection is a substantial problem in herds of domestic cattle worldwide and a rising threat in human disease. Application of comparative and functional genomics approaches will be essential to understand the molecular basis of this pathogen's interactions with various hosts. Here we report recent progress in genome analyses of C. fetus(More)
Bacterial conjugation is a form of type IV secretion used to transport protein and DNA directly to recipient bacteria. The process is cell contact-dependent, yet the mechanisms enabling extracellular events to trigger plasmid transfer to begin inside the cell remain obscure. In this study of plasmid R1 we investigated the role of plasmid proteins in the(More)
Bacterial conjugation disseminates genes among bacteria via a process requiring direct cell contact. The cell envelope spanning secretion apparatus involved belongs to the type IV family of bacterial secretion systems, which transport protein as well as nucleoprotein substrates. This study aims to understand mechanisms leading to the initiation of type IV(More)
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