Plasmodium protein phosphatase 2C dephosphorylates translation elongation factor 1beta and inhibits its PKC-mediated nucleotide exchange activity in vitro.
The elongation step of protein synthesis involves binding of aminoacyl-tRNA to the ribosomal A site, formation of a peptide bond and translocation of the newly formed peptidyl-tRNA to the P site. The nucleotide exchange factor EF-1beta plays a major role in the regulation of this process by regenerating a GTP-bound EF-1alpha necessary for each elongation cycle. EF-1beta has been shown to be phosphorylated and its phosphorylation is critical for optimal activity. We have previously identified a serine/threonine protein phosphatase 2C (PP2C) from the human malaria parasite Plasmodium falciparum. In the current work, we performed Far-Western analysis to identify PfPP2C substrates. Several components of the translation and transcription machinery were identified, including translation elongation factor 1-beta (PfEF-1beta). PfEF-1beta is efficiently phosphorylated by protein kinase C and this phosphorylation results in a 400% increase in its nucleotide exchange activity. PKC-phosphorylated PfEF-1beta is readily and selectively dephosphorylated by recombinant and native PfPP2C, which downregulates the nucleotide exchange activity to its basal level. The identification of a translation elongation component as substrate for PP2C suggests an important regulatory function for this enzyme and suggests that it may be a good target for drug design in the fight against malaria.
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Howard Hughes Medical Institute, Washington University School of Medicine, Departments of Medicine and Molecular Microbiology, 660 S Euclid Avenue, Box 8230, St. Louis, MO 63110, USA.
Goldberg
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D000595:Amino Acid Sequence; D000818:Animals; D008969:Molecular Sequence Data; D009711:Nucleotides; D020648:Peptide Elongation Factor 1 / Q000096:biosynthesis* / Q000235:genetics; D010749:Phosphoprotein Phosphatases / Q000378:metabolism*; D010766:Phosphorylation; D010963:Plasmodium falciparum / Q000201:enzymology*; D011493:Protein Kinase C / Q000378:metabolism*; D054648:Protein Phosphatase 2; D000071636:Protein Phosphatase 2C; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity
D009711:Nucleotides; D020648:Peptide Elongation Factor 1; D029701:Saccharomyces cerevisiae Proteins; D011493:Protein Kinase C; C000607456:PPM1A protein, human; C000607457:PPM1B protein, human; C000607460:PPM1G protein, human; C087358:PTC1 protein, S cerevisiae; D010749:Phosphoprotein Phosphatases; D054648:Protein Phosphatase 2; D000071636:Protein Phosphatase 2C