Calcium-sensitive pyruvate dehydrogenase phosphatase is required for energy metabolism, growth, differentiation, and infectivity of Trypanosoma cruzi

J Biol Chem. 2018 Nov 9;293(45):17402-17417. doi: 10.1074/jbc.RA118.004498. Epub 2018 Sep 19.

Abstract

In vertebrate cells, mitochondrial Ca2+ uptake by the mitochondrial calcium uniporter (MCU) leads to Ca2+-mediated stimulation of an intramitochondrial pyruvate dehydrogenase phosphatase (PDP). This enzyme dephosphorylates serine residues in the E1α subunit of pyruvate dehydrogenase (PDH), thereby activating PDH and resulting in increased ATP production. Although a phosphorylation/dephosphorylation cycle for the E1α subunit of PDH from nonvertebrate organisms has been described, the Ca2+-mediated PDP activation has not been studied. In this work, we investigated the Ca2+ sensitivity of two recombinant PDPs from the protozoan human parasites Trypanosoma cruzi (TcPDP) and T. brucei (TbPDP) and generated a TcPDP-KO cell line to establish TcPDP's role in cell bioenergetics and survival. Moreover, the mitochondrial localization of the TcPDP was studied by CRISPR/Cas9-mediated endogenous tagging. Our results indicate that TcPDP and TbPDP both are Ca2+-sensitive phosphatases. Of note, TcPDP-KO epimastigotes exhibited increased levels of phosphorylated TcPDH, slower growth and lower oxygen consumption rates than control cells, an increased AMP/ATP ratio and autophagy under starvation conditions, and reduced differentiation into infective metacyclic forms. Furthermore, TcPDP-KO trypomastigotes were impaired in infecting cultured host cells. We conclude that TcPDP is a Ca2+-stimulated mitochondrial phosphatase that dephosphorylates TcPDH and is required for normal growth, differentiation, infectivity, and energy metabolism in T. cruzi Our results support the view that one of the main roles of the MCU is linked to the regulation of intramitochondrial dehydrogenases.

Keywords: CRISPR/Cas9; Trypanosoma cruzi; bioenergetics; calcium; calcium signaling; energy metabolism; mitochondrial calcium uniporter; mitochondrial dehydrogenase; pyruvate dehydrogenase phosphatase.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Line
  • Chagas Disease / enzymology*
  • Chagas Disease / genetics
  • Chagas Disease / pathology
  • Energy Metabolism*
  • Gene Knockdown Techniques
  • Humans
  • Ketone Oxidoreductases / genetics
  • Ketone Oxidoreductases / metabolism*
  • Phosphorylation / genetics
  • Protozoan Proteins / genetics
  • Protozoan Proteins / metabolism*
  • Trypanosoma cruzi / enzymology*
  • Trypanosoma cruzi / genetics

Substances

  • Protozoan Proteins
  • Ketone Oxidoreductases
  • pyruvate dehydrogenase (NADP+)