Metabolic functions of glycosomes in trypanosomatids.
Protozoan Kinetoplastida, including the pathogenic trypanosomatids of the genera Trypanosoma and Leishmania, compartmentalize several important metabolic systems in their peroxisomes which are designated glycosomes. The enzymatic content of these organelles may vary considerably during the life-cycle of most trypanosomatid parasites which often are transmitted between their mammalian hosts by insects. The glycosomes of the Trypanosoma brucei form living in the mammalian bloodstream display the highest level of specialization; 90% of their protein content is made up of glycolytic enzymes. The compartmentation of glycolysis in these organelles appears essential for the regulation of this process and enables the cells to overcome short periods of anaerobiosis. Glycosomes of all other trypanosomatid forms studied contain an extended glycolytic pathway catalyzing the aerobic fermentation of glucose to succinate. In addition, these organelles contain enzymes for several other processes such as the pentose-phosphate pathway, beta-oxidation of fatty acids, purine salvage, and biosynthetic pathways for pyrimidines, ether-lipids and squalenes. The enzymatic content of glycosomes is rapidly changed during differentiation of mammalian bloodstream-form trypanosomes to the forms living in the insect midgut. Autophagy appears to play an important role in trypanosomatid differentiation, and several lines of evidence indicate that it is then also involved in the degradation of old glycosomes, while a population of new organelles containing different enzymes is synthesized. The compartmentation of environment-sensitive parts of the metabolic network within glycosomes would, through this way of organelle renewal, enable the parasites to adapt rapidly and efficiently to the new conditions.
Michels
Paul A M
PA
Research Unit for Tropical Diseases, Christian de Duve Institute of Cellular Pathology and Laboratory of Biochemistry, Université catholique de Louvain, ICP-TROP 74.39, Avenue Hippocrate 74, B-1200 Brussels, Belgium. michels@bchm.ucl.ac.be
Bringaud
Frédéric
F
Herman
Murielle
M
Hannaert
Véronique
V
D000818:Animals; D002451:Cell Compartmentation; D002454:Cell Differentiation; D006019:Glycolysis; D007891:Leishmania / Q000378:metabolism*; D008830:Microbodies / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism; D015800:Protozoan Proteins / Q000378:metabolism*; D014345:Trypanosoma / Q000378:metabolism*; D014346:Trypanosoma brucei brucei / Q000378:metabolism
D015800:Protozoan Proteins