Organelles in Blastocystis that blur the distinction between mitochondria and hydrogenosomes.
van der Giezen, M
Blastocystis is a unicellular stramenopile of controversial pathogenicity in humans. Although it is a strict anaerobe, Blastocystis has mitochondrion-like organelles with cristae, a transmembrane potential and DNA. An apparent lack of several typical mitochondrial pathways has led some to suggest that these organelles might be hydrogenosomes, anaerobic organelles related to mitochondria. We generated 12,767 expressed sequence tags (ESTs) from Blastocystis and identified 115 clusters that encode putative mitochondrial and hydrogenosomal proteins. Among these is the canonical hydrogenosomal protein iron-only [FeFe] hydrogenase that we show localizes to the organelles. The organelles also have mitochondrial characteristics, including pathways for amino acid metabolism, iron-sulfur cluster biogenesis, and an incomplete tricarboxylic acid cycle as well as a mitochondrial genome. Although complexes I and II of the electron transport chain (ETC) are present, we found no evidence for complexes III and IV or F1Fo ATPases. The Blastocystis organelles have metabolic properties of aerobic and anaerobic mitochondria and of hydrogenosomes. They are convergently similar to organelles recently described in the unrelated ciliate Nyctotherus ovalis. These findings blur the boundaries between mitochondria, hydrogenosomes, and mitosomes, as currently defined, underscoring the disparate selective forces that shape these organelles in eukaryotes.
addresses: Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, B3H 1X5, Canada. email@example.com
notes: PMCID: PMC2428068
types: Journal Article; Research Support, Non-U.S. Gov't
Open Access Article. This is a copy of an article published in Current Biology © Elsevier. Current Biology is available online at: http://www.sciencedirect.com/science/journal/09609822
Current Biology, 2008, Vol. 18, Issue 8, pp. 580 - 585
Place of publication