The Proteome of T. vaginalis Hydrogenosomes

Abstract

Trichomonas vaginalis and related organisms of Parabasalia group possess anaerobic forms of mitochondria named hydrogenosomes. These organelles lost most of mitochondrial pathways during adaptation to anaerobic lifestyle. Proteomic analysis of hydrogenosomes purified from T. vaginalis and more recently from Pentatrichomonas hominis revealed that trichomonad hydrogenosomes consist of about 600 proteins, which is about half of proteins present in yeast mitochondria. Matrix proteins of known function that account for about 19% of the proteome include enzymes of energy metabolism, components of Fe-S cluster assembly, oxygen and xenobiotic stress response, amino acid metabolism, proteolytic enzymes, and chaperones. Approximately 11% of the proteome represent membrane components of protein import machinery and other membrane proteins. Three large protein groups consist of hypothetical proteins (20%), miscellaneous proteins (16%), and proteins that might be associated with outer hydrogenosomal membrane (34%). The proteome is highly redundant, which reflects the presence of multiple gene copies for most of proteins in trichomonad genome. Interestingly, most of paralogues are expressed and identified in the proteome. However, the protein level of individual paralogues is rather variable, and iron availability appears to be an important factor in regulation of the proteome composition.