Investigation of structure and function of bacterial porins with special emphasis on their role in physiology of Borrelia and related species

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The cytoplasm of gram-negative bacteria is surrounded by two membranes. The outer membranes serve as molecular filters. The filter properties are either general or specific. Small hydrophilic molecules pass these membranes with high velocity through channels that are known as bacterial porins. The project will deal with the study of these porin channels with special emphasis on the study of outer membrane channels of Borrelia and related Spirochetes, which are not well characterized to date. Borrelia are the cause of different diseases transmitted by the bites of parasites. For example Borrelia burgdorferi is the etiologic agent of Lyme borreliosis and is spread by Ixodes tics. Old world tick-borne relapsing fever (TBRF), caused in humans by the bite of an infected soft body tick Ornithodorus moubata transmitting the pathogen Borrelia duttonii, is a common endemic disease in Central, East and South Africa. Other pathogenic Borrelia species such as B. hermsii and B. recurrentis are also transmitted by tics or are louse-born. Borrelia spirochetes are hostpropagated bacteria that cycle between warm-blooded and arthropod hosts and have therefore developed advanced strategies to sense and survive in these environments. Uptake of nutrients through the outer membrane of Borrelia in different hosts plays an important role in the lifestyle of these bacteria because they have an only limited metabolic capacity. This means that the transport of nutrients through porins is very for important for survival of Borrelia in their hosts. Outer membrane porins in different Borrelia species and other Spirochetes should be identified, isolated, purified and characterized by different biochemical and biophysical methods. Molecular biology will be used to identify and clone porin genes. Porin genes should be recombinantly expressed in Escherichia coli for further analysis of the porin channels in different biochemical and biophysical approaches.