Hydrogenosomes and their metabolic enzymes,
molecular phylogenetic considerations
Horner, D.S., van der Giezen, M., Embley, T. M.
Dept of Zoology, The Natural History Museum, Cromwell Rd, London SW7 5BD,
United Kingdom
Hydrogenosomes are energy generating organelles which are found in a variety of anaerobic microbial eukaryotes. Phylogenetic considerations indicate the polyphyletic nature of the the occurence of these organelles. However, recent morphological, biochemical and molecular data suggest that modification of a pre-existing organelle (the mitochondrion) may account for the biogenesis of the hydrogenosomal compartment in diverse taxa. Under this scenario, loss of enzymes required for oxidative phosphorylation is accompanied by the apparent acquisition of at least two highly oxygen sensitive enzyme activities involved in the production of molecular hydrogen. These activities (Pyruvate-ferredoxin oxidoreductase and Hydrogenase) are not considered to be typical of mitochondrial energy metabolism. Their apparent presence in all hydrogenosomal organisms requires explanation in the context of the mitochondrial conversion hypothesis.
Here I will briefly review data relating to the evolution of hydrogenosomes in Parabasalids, Ciliates and anaerobic fungi, the three best studied systems. In addition, the nature and possible origins of Pyruvate-ferredoxin oxidoreductase, an oxygen sensitive activity believed to be common to all hydrogenosomes, will be examined.
| LOCATION |
DATE |
TIME |
| Lecture Hall I |
Wednesday, April 8 |
02:40 pm |