Characterization of a UBC13 kinase in Plasmodium falciparum.

Journal Article (Journal Article)

Protein kinases are generally recognized as attractive drug targets to treat a variety of human diseases. Recent analysis of the Plasmodium falciparum kinome identified several kinases that are entirely unique to Plasmodium species. The specific functions and targets of most of these enzymes remain largely unknown. Here, we have identified a P. falciparum kinase (PfPK9/PF13_0085 ORF) that does not cluster with any of the typical eukaryotic protein kinases. PfPK9 protein expression was induced approximately 18 h after red blood cell infection, and was mainly localized to the parasitophorous vacuolar membrane as well as the cytosol. Recombinant PfPK9 autophosphorylated in vitro and specifically phosphorylated the exogenous substrate histone H1, indicating that it is catalytically active. Phosphopeptide mapping studies showed that autophosphorylation occurred at three residues: T082, T265, and T269. We identified a P. falciparum homolog of the E2 ubiquitin-conjugating enzyme 13 (UBC13) as an endogenous substrate for PfPK9. PfPK9 phosphorylated UBC13 at S106, a highly conserved residue among eukaryotic E2s, and suppressed its ubiquitin-conjugating activity. Our findings not only describe a previously uncharacterized Plasmodium kinase and its likely in vivo target, but also suggest that modulation of UBC13 activity by phosphorylation may be a common regulatory mechanism in eukaryotes.

Full Text

Duke Authors

Cited Authors

  • Philip, N; Haystead, TA

Published Date

  • May 8, 2007

Published In

Volume / Issue

  • 104 / 19

Start / End Page

  • 7845 - 7850

PubMed ID

  • 17452636

Pubmed Central ID

  • PMC1876535

International Standard Serial Number (ISSN)

  • 0027-8424

Digital Object Identifier (DOI)

  • 10.1073/pnas.0611601104


  • eng

Conference Location

  • United States