Comparative analysis of K+-channels from two Chlorella species: information on their role in endosymbiosis and on the origin of viral K+-channels

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Currently the genomes of two Chlorella species are fully sequenced. The applicant is part of an international project, which is involved in their comparative analysis. One species, Cholrella vulgaris, is a typical free living organism, while the other one, C. NC64A, is a endosymbiont of Paramecium bursaria; unlike the former C. NC64A is also a host for Chlorella viruses. The goal is to identify the K+-channels in the two Chlorella genomes. This will answer the question whether or not the miniature K+-channel genes found in many Chlorella viruses are the result of molecular piracy from their host. This is an important issue for understanding the direction of gene fluxes between viruses and hosts. A comparative analysis together with expression studies will further answer the question whether or not K+-channels with different functional properties are required for the endosymbiotic versus the free style of living. Screening of the two genomes has already uncovered K+-channel like sequences with unusual structures; one for example has the hallmarks of a K+-channel but does not carry parts of the K+-channel signature sequence. Cloning and structure/ function analysis of these unusual channel proteins will uncover interesting information on alternative architectures of K+-channels.