Meeting Abstract

116.5  Monday, Jan. 7  A mitochondrial sponge gene unique among animals: the evolution of the Tat pathway in Oscarella PETT, W*; LAVROV, D; Iowa State University; Iowa State University willpett@iastate.edu

The twin-arginine translocation (Tat) pathway is a protein transport system that serves in moving folded proteins across energy-transducing membranes, and is widespread in all domains of life. Genes encoding different components of the pathway have been found in the genomes of many bacteria, archaea, plants, and plant mitochondria. However, the same genes have been lost from most other mitochondrial genomes, including nearly all animals. The only exception in animals is the homoscleromorph sponges in the genus Oscarella (family Oscarellidae), whose mitochondrial genomes encode a gene for TatC, the subunit with the largest number of transmembrane helices. However, the functional significance of the presence of this gene in Oscarellidae remains unclear. Here we characterize the genetic makeup of the Tat pathway in Oscarellid sponges, and address the origin and evolution of the mitochondrial TatC gene. Since previous studies have found the entire Tat pathway to be missing from mammalian genomes, we will address the question of whether other components of the Tat pathway have been transferred to the nucleus in Oscarellidae, or if TatC is operating alone with a possibly different function. The possibility that the Tat pathway was inherited from the ancestral eukaryotic mitochondrial genome and is present in Oscarellidae would imply multiple independent losses of the entire mitochondrial Tat pathway during the evolution of animals, and an unprecedented high rate of loss for an animal mitochondrial gene.