Post-translational modification of the pyruvate phosphate dikinase from Trypanosoma cruzi.
In kinetoplastids such as Trypanosoma cruzi, glycolysis is compartmentalized in peroxisome-like organelles called glycosomes. Pyruvate phosphate dikinase (PPDK), an auxiliary enzyme of glycolysis, is also located in the glycosomes. We have detected that this protein is post-translationally modified by phosphorylation and proteolytic cleavage. On western blots of T. cruzi epimastigotes, two PPDK forms were found with apparent MW of 100 kDa and 75 kDa, the latter one being phosphorylated at Thr481, a residue present in a highly conserved region. In subcellular localization assays the 75 kDa PPDK was located peripherally at the glycosomal membrane. Both PPDK forms were found in all life-cycle stages of the parasite. When probing for both PPDK forms during a growth of epimastigotes in batch culture, an increase in the level of the 75 kDa form and a decrease of the 100 kDa one were observed by western blot analysis, signifying that glucose starvation and the concomitant switch of the metabolism to amino acid catabolism may play a role in the post-translational processing of the PPDK. Either one or both of the processes, phosphorylation and proteolytic cleavage of PPDK, result in inactivation of the enzyme. It remains to be established whether the phenomenon exerts a regulatory function.
Laboratorio de Enzimología de Parásitos, Facultad de Ciencias, Universidad de Los Andes, La Hechicera, Mérida 5101, Venezuela. Electronic address: ebgonzal@ivic.gob.ve.
Eglys
E
González-Marcano
Alfredo
A
Mijares
Wilfredo
W
Quiñones
Ana
A
Cáceres
Juan Luis
JL
Concepción
D000595:Amino Acid Sequence; D000818:Animals; D017124:Conserved Sequence; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology*; D008027:Light; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011772:Pyruvate, Orthophosphate Dikinase / Q000235:genetics / Q000378:metabolism*; D012323:RNA Processing, Post-Transcriptional / Q000502:physiology*; D014349:Trypanosoma cruzi / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism
D011772:Pyruvate, Orthophosphate Dikinase
Glycosome; Phosphorylation; Pyruvate phosphate dikinase; Trypanosoma cruzi