Compartmentation prevents a lethal turbo-explosion of glycolysis in trypanosomes.
ATP generation by both glycolysis and glycerol catabolism is autocatalytic, because the first kinases of these pathways are fuelled by ATP produced downstream. Previous modeling studies predicted that either feedback inhibition or compartmentation of glycolysis can protect cells from accumulation of intermediates. The deadly parasite Trypanosoma brucei lacks feedback regulation of early steps in glycolysis yet sequesters the relevant enzymes within organelles called glycosomes, leading to the proposal that compartmentation prevents toxic accumulation of intermediates. Here, we show that glucose 6-phosphate indeed accumulates upon glucose addition to PEX14 deficient trypanosomes, which are impaired in glycosomal protein import. With glycerol catabolism, both in silico and in vivo, loss of glycosomal compartmentation led to dramatic increases of glycerol 3-phosphate upon addition of glycerol. As predicted by the model, depletion of glycerol kinase rescued PEX14-deficient cells of glycerol toxicity. This provides the first experimental support for our hypothesis that pathway compartmentation is an alternative to allosteric regulation.
Haanstra
Jurgen R
JR
Department of Molecular Cell Physiology, Faculty of Earth and Life Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1085, NL-1081 HV, Amsterdam, The Netherlands.
van Tuijl
Arjen
A
Kessler
Peter
P
Reijnders
Willem
W
Michels
Paul A M
PA
Westerhoff
Hans V
HV
Parsons
Marilyn
M
Bakker
Barbara M
BM
D000818:Animals; D002384:Catalysis / Q000187:drug effects; D002451:Cell Compartmentation / Q000187:drug effects; D005947:Glucose / Q000494:pharmacology; D019298:Glucose-6-Phosphate / Q000378:metabolism; D005990:Glycerol / Q000633:toxicity; D005991:Glycerol Kinase / Q000172:deficiency; D006019:Glycolysis / Q000187:drug effects; D008565:Membrane Proteins / Q000378:metabolism; D008830:Microbodies / Q000187:drug effects / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D010641:Phenotype; D021381:Protein Transport / Q000187:drug effects; D015800:Protozoan Proteins / Q000378:metabolism; D019289:Pyruvic Acid / Q000378:metabolism; D034622:RNA Interference / Q000187:drug effects; D013347:Subcellular Fractions / Q000187:drug effects / Q000201:enzymology; D014346:Trypanosoma brucei brucei / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*
D008565:Membrane Proteins; C468927:PEX14 protein, Trypanosoma brucei; D015800:Protozoan Proteins; D019298:Glucose-6-Phosphate; D019289:Pyruvic Acid; D005991:Glycerol Kinase; D005947:Glucose; D005990:Glycerol