Targeting and translocation of proteins into the hydrogenosome
of the protist Trichomonas: similarities with mitochondrial protein import.
Their thinking stems in large part from recently gathered information about the ancestry of the hydrogenosome
. Observed for decades in cells as rodlike objects resembling mitochondria but lacking their own DNA, "they were looked at as a curiosity, an oddball organelle.
In the case of the trichomonads the proteins have been localized to the hydrogenosome
(10), an energy-generating organelle that already had been suspected by some of having mitochondrial origins.
Review Article: The hydrogenosome
. J Gen Microbiol 1993; 139(12): 2879-2889.
According to previous reports, lactate, formate, ethanol and succinate were formed in the cytosol of anaerobic fungi, and acetate, formate and [H.sub.2]/C[O.sub.2] were formed in the hydrogenosome
(O'Fallon et al., 1991; Akhmanova et al., 1999; Boxma et al., 2004).
, a cytoplasmic organelle of the anaerobic flagellate Tritrichomonas foetus, and its role in pyruvate metabolism.
The anaerobic fungi are amitochondrial organisms and have a hydrogenosome
instead for energy production (Yarlett et al., 1986).
Parabasalia are clearly secondarily amitochondrial, since their hydrogenosomes
probably evolved from mitochondria by the loss of cytochromes and DNA; protein phylogeny ((4); Hasegawa, pers.
in some anaerobic protozoa resemble mitochondria.
Some one-celled creatures depend on such organisms to take the hydrogen, along with other products, from the hydrogenosomes
and turn it into user-friendly metabolites for the host cell (SN: 4/18/98, p.
The Parabasalia is composed of flagellated anaerobic protists defined by the presence of hydrogenosomes
, flagellar apparatus, parabasal body, and parabasal filament.
contain the NADH dehydrogenase module of mitochondrial complex I.