[Seminar] "Bacterial type V secretion systems: structure, function, and evolution" by Prof. Dirk Linke
Speaker: Prof. Dirk Linke, Department of Biosciences, University of Oslo, Norway
Title: Bacterial type V secretion systems: structure, function, and evolution
Type V secretion systems are ubiquitous in Gram-negative bacteria. Compared to other bacterial secretion systems, they are surprisingly simple, often consisting only of one polypeptide chain. This polypeptide consists of two functionally important domains, the translocator domain that inserts in the Gram-negative outer membrane, and the passenger domain that is secreted to the cell surface. The passenger domain, after secretion, often fulfils key roles in pathogenesis or in symbiotic relationships with specific hosts . The translocator domain remains in the outer membrane, and serves as an anchor .
In this presentation, I will discuss the different subtypes of type V secretion systems, that have not only different structure and slight differences in translocation mechanism, but also fulfil a broad variety of functions for the bacteria. As they are exposed to the immune system in the case of bacterial pathogens, they are under significant evolutionary pressure. This makes them interesting examples for the study of protein evolution. They display large sequence variety even between closely related strains and species, and often swap and shuffle their domains to escape detection. Last but not least, I will discuss some molecular details of how these proteins insert into the outer membrane to initiate the secretion of the passenger domain. I will discuss the common principles that they share with other transmembrane beta-barrel proteins in this regard .
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