Mobility endonucleases are known to promote gene conversion events in a broad range of organisms including yeast, the T-even bacteriophages T2, T4 and T6, the acellular slime mold Physarum polycephalum and the green algae Chlamydomonas. They present a minimum of two new classes of DNA-cleavage proteins based on analysis of their complex recognition sites and their amino acid sequences. Their role in intra-species gene conversion events has already been established, while their potential involvement in horizontal gene transfer and in mitochondrially related fungal senescence is under investigation. The objective of this research planning grant is to first establish a working system of genetic and molecular techniques and assays to study the intron-encoded mitochondrial endonucleases in Podospora anserina, and to initiate the proposed study with a specific endonuclease candidate. These preliminary efforts will provide the basis for additional studies that will 1) address the frequency of mobility endonucleases within the mitochondria of Podospora, 2) characterize selected endonucleases in regard to their substrate requirements and specificity, 3) study the expression and regulation of these proteins and their function in the mitochondria, 4) develop techniques to look at the possible acquisition of introns and their mobility endonucleases via horizontal transfer, and 5) assess their possible role in senescence- a curious aging process that Podospora exhibit during culture.
