Mitosomes represent the simplest forms of mitochondria. The long independent evolution of the mitosomes bearing unicellular eukaryotes like Giardia intestinalis transformed mitochondria into tiny double membrane bound vesicles, which have lost organellar genome, respiratory chain as well as the capacity to generate ATP.
While publication of G. intestinalis genome sequence has brought great source of data for deciphering mitosomal functions, biochemical approaches have struggled with difficulties in organlee isolation techniques due to its miniature size and low abundance. Thus to date the sole metabolic pathway harbored in the G. intestinalis mitosomes is the formation of FeS clusters.
This chapter reviews recent successes in the research of these fascinating organelles and proposes perspective research directions.