Interaction network of the 14-3-3 protein in the ancient protozoan parasite Giardia duodenalis

J Proteome Res. 2012 May 4;11(5):2666-83. doi: 10.1021/pr3000199. Epub 2012 Apr 11.


14-3-3s are phosphoserine/phosphotreonine binding proteins that play pivotal roles as regulators of multiple cellular processes in eukaryotes. The flagellated protozoan parasite Giardia duodenalis, the causing agent of giardiasis, is a valuable simplified eukaryotic model. A single 14-3-3 isoform (g14-3-3) is expressed in Giardia, and it is directly involved in the differentiation of the parasite into cyst. To define the overall functions of g14-3-3, the protein interactome has been investigated. A transgenic G. duodenalis strain was engineered to express a FLAG-tagged g14-3-3 under its own promoter. Affinity chromatography coupled with tandem mass spectrometry analysis have been used to purify and identify FLAG-g14-3-3-associated proteins from trophozoites and encysting parasites. A total of 314 putative g14-3-3 interaction partners were identified, including proteins involved in several pathways. Some interactions seemed to be peculiar of one specific stage, while others were shared among the different stages. Furthermore, the interaction of g14-3-3 with the giardial homologue of the CDC7 protein kinase (gCDC7) was characterized, leading to the identification of a multiprotein complex containing not only g14-3-3 and gCDC7 but also a newly identified and highly divergent homologue of DBF4, the putative regulatory subunit of gCDC7. The relevance of g14-3-3 interactions in G. duodenalis biology was discussed.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 14-3-3 Proteins / genetics
  • 14-3-3 Proteins / metabolism*
  • Amino Acid Motifs
  • Binding Sites
  • Cell Cycle Proteins / genetics
  • Cell Cycle Proteins / metabolism
  • Chromatography, Affinity
  • DNA, Protozoan / genetics
  • Escherichia coli / genetics
  • Escherichia coli / metabolism
  • Giardia lamblia / genetics
  • Giardia lamblia / metabolism*
  • Immunoprecipitation
  • Ligands
  • Multiprotein Complexes / genetics
  • Multiprotein Complexes / metabolism
  • Organisms, Genetically Modified / genetics
  • Organisms, Genetically Modified / metabolism
  • Promoter Regions, Genetic
  • Protein Interaction Mapping
  • Protein Interaction Maps*
  • Protein-Serine-Threonine Kinases / genetics
  • Protein-Serine-Threonine Kinases / metabolism*
  • Proteome / analysis
  • Protozoan Proteins / genetics
  • Protozoan Proteins / metabolism*
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Tandem Mass Spectrometry
  • Transfection


  • 14-3-3 Proteins
  • Cell Cycle Proteins
  • DNA, Protozoan
  • Ligands
  • Multiprotein Complexes
  • Proteome
  • Protozoan Proteins
  • Recombinant Fusion Proteins
  • Protein-Serine-Threonine Kinases