Plasmodium food vacuole plasmepsins are activated by falcipains

J Biol Chem. 2008 May 9;283(19):12870-6. doi: 10.1074/jbc.M708949200. Epub 2008 Feb 28.

Abstract

Intraerythrocytic malaria parasites use host hemoglobin as a major nutrient source. Aspartic proteases (plasmepsins) and cysteine proteases (falcipains) function in the early steps of the hemoglobin degradation pathway. There is extensive functional redundancy within and between these protease families. Plasmepsins are synthesized as integral membrane proenzymes that are activated by cleavage from the membrane. This cleavage is mediated by a maturase activity whose identity has been elusive. We have used a combination of cell biology, chemical biology, and enzymology approaches to analyze this processing event. These studies reveal that plasmepsin processing occurs primarily via the falcipains; however, if falcipain activity is blocked, autoprocessing can take place, serving as an alternate activation system. These results establish a further level of redundancy between the protease families involved in Plasmodium hemoglobin degradation.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Aspartic Acid Endopeptidases / metabolism*
  • Cysteine Endopeptidases / metabolism*
  • Enzyme Activation
  • Kinetics
  • Leucine / analogs & derivatives
  • Leucine / pharmacology
  • Mass Spectrometry
  • Pepstatins / metabolism
  • Peptide Fragments / chemistry
  • Peptide Fragments / metabolism
  • Plasmodium falciparum / cytology*
  • Plasmodium falciparum / drug effects
  • Plasmodium falciparum / enzymology*
  • Vacuoles / enzymology*

Substances

  • Pepstatins
  • Peptide Fragments
  • Cysteine Endopeptidases
  • falcipain
  • Aspartic Acid Endopeptidases
  • plasmepsin
  • Leucine
  • E 64
  • pepstatin