Plasmodium falciparum Cyclic GMP-Dependent Protein Kinase Interacts with a Subunit of the Parasite Proteasome.
Infect Immun
; 87(1)2019 01.
Article
em En
| MEDLINE
| ID: mdl-30323024
ABSTRACT
Malaria is caused by the protozoan parasite Plasmodium, which undergoes a complex life cycle in a human host and a mosquito vector. The parasite's cyclic GMP (cGMP)-dependent protein kinase (PKG) is essential at multiple steps of the life cycle. Phosphoproteomic studies in Plasmodium falciparum erythrocytic stages and Plasmodium berghei ookinetes have identified proteolysis as a major biological pathway dependent on PKG activity. To further understand PKG's mechanism of action, we screened a yeast two-hybrid library for P. falciparum proteins that interact with P. falciparum PKG (PfPKG) and tested peptide libraries to identify its phosphorylation site preferences. Our data suggest that PfPKG has a distinct phosphorylation site and that PfPKG directly phosphorylates parasite RPT1, one of six AAA+ ATPases present in the 19S regulatory particle of the proteasome. PfPKG and RPT1 interact in vitro, and the interacting fragment of RPT1 carries a PfPKG consensus phosphorylation site; a peptide carrying this consensus site competes with the RPT1 fragment for binding to PfPKG and is efficiently phosphorylated by PfPKG. These data suggest that PfPKG's phosphorylation of RPT1 could contribute to its regulation of parasite proteolysis. We demonstrate that proteolysis plays an important role in a biological process known to require Plasmodium PKG invasion by sporozoites of hepatocytes. A small-molecule inhibitor of proteasomal activity blocks sporozoite invasion in an additive manner when combined with a Plasmodium PKG-specific inhibitor. Mining the previously described parasite PKG-dependent phosphoproteomes using the consensus phosphorylation motif identified additional proteins that are likely to be direct substrates of the enzyme.
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01-internacional
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MEDLINE
Assunto principal:
Plasmodium falciparum
/
Proteínas Quinases Dependentes de GMP Cíclico
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Mapeamento de Interação de Proteínas
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Complexo de Endopeptidases do Proteassoma
Idioma:
En
Revista:
Infect Immun
Ano de publicação:
2019
Tipo de documento:
Article
País de afiliação:
Estados Unidos