Mitochondrion-Related Organelles in Eukaryotic Protists

Abstract

The discovery of mitochondrial-type genes in organisms thought to lack mitochondria led to the demonstration that hydrogenosomes share a common ancestry with mitochondria, as well as the discovery of mitosomes in multiple eukaryotic lineages. No examples of examined eukaryotes lacking a mitochondrion-related organelle exist, implying that the endosymbiont that gave rise to the mitochondrion was present in the first eukaryote. These organelles, known as hydrogenosomes, mitosomes or mitochondrion-like organelles (MLO), are typically reduced, both structurally and biochemically, relative to classical mitochondria. However, despite diversification and adaptation to different niches, all appear to play a role in Fe-S cluster assembly, as observed for mitochondria. Although evidence supports the use of common protein targeting mechanisms in the biogenesis of these diverse organelles, divergent features are also apparent. The metabolism and biogenesis of these organelles in parasitic protists is discussed here.

A Machine Learning Approach To Identify Hydrogenosomal Proteins in Trichomonas vaginalis

“…The hydrogenosomal localization of only 30 proteins has been verified experimentally (11,53,63,64,79). The current estimate is significantly lower than the ϳ500 proteins expected to be found in the hydrogenosome (73). This is compounded by the finding that some HTS-lacking proteins are imported into hydrogenosomes, the alpha subunit of succinyl-coenzyme A (CoA) synthetase (TVAG_165340), and a thioredoxin reductase isoform (TVAG_125360) (53).…”

“…Only a few homologs of mitochondrial import machinery components have been identified in T. vaginalis. Two of these were shown to localize to the outer hydrogenosomal membrane (Hmp35 and Sam50) (18,73). Import of precursors was shown to be ATP dependent, and early in vitro analyses suggested that correct targeting requires an N-terminal leader (9,11), referred to in this article as a hydrogenosomal targeting signal sequence (HTS).…”

Biochemistry and Evolution of Anaerobic Energy Metabolism in Eukaryotes

“…Numerous aspects of the mitochondria of anaerobes and parasites have recently been reviewed elsewhere, including protein import (121), FeS cluster assembly (454,520), bioenergetic aspects (266,267), and reductive evolutionary trends (193). Monographs on the topic of hydrogenosomes and mitosomes have appeared (84,310,480), as have books on the evolutionary significance of mitochondria, including anaerobic forms (264,265).…”

The biological activity of high-density lipoprotein fractions and their role in the development of cardiovascular diseases

“…Трипаносомный литический фактор выделен из плазмы как незначительная фракция плотных частиц ЛПВП молекуляр-ной массой 490 кДа, диаметром 15-21 нм и поверхностной плот-ностью 1,21-1,24 г/мл [73,74]. В дополнение к апоL1, белку, связывающему гемоглобин, гаптоглобину связанных белков (Hrp) и апоА1, комплекс, по-видимому, также содержит апоA2, апоС1, апоС2 и апоС3 [75].…”