PF3D7_1033900

PF3D7_1033900 (E2) is the SUMO-conjugating E2 enzyme (Ubc9) of the Plasmodium falciparum SUMOylation pathway, functioning in the enzymatic cascade downstream of the parasite SUMO-activating E1 enzyme (PMID:26697886). Structural and biochemical characterization of the P. falciparum SUMO E1–E2 interaction identified surface residues that render the E1–E2 interface distinct from its human counterpart, defining species-specific determinants of complex formation (PMID:26697886). The cross-species compatibility of E2 is asymmetric: Pf-SUMO can engage human E2, but human SUMO1 fails to interact with Pf-E2, a restriction imposed by critical N-terminal residues of Pf-E2 whose mutation to the corresponding human Ubc9 residues restores efficient interaction by recovering electrostatic, π-π, and hydrophobic contacts (PMID:35331687). Beyond these interface-mapping studies, the catalytic cycle, substrate repertoire, and in vivo role of PF3D7_1033900 in the parasite have not been characterized in the available corpus.

1. 2015 High

   Whether the parasite SUMOylation cascade could be selectively targeted was unknown; mapping the SUMO E1–E2 interface established that P. falciparum uses species-specific surface residues distinct from the human enzymes.

   Evidence X-ray crystallography of the human SUMO E1 UFD–E2 complex with in silico modeling, site-directed mutagenesis, and in vitro biochemistry of the P. falciparum E1 and E2 enzymes

   PMID:26697886

   Open questions at the time

   • No structure of the P. falciparum E1–E2 complex itself was solved (interface inferred by modeling from the human structure)
   • Catalytic mechanism and E2~SUMO thioester chemistry not characterized
   • No in vivo confirmation that these residues govern SUMOylation in the parasite
2. 2022 Medium

   The molecular basis for whether parasite and human SUMO machinery are interchangeable was open; biophysical mapping showed a unidirectional cross-species interaction dictated by N-terminal residues of Pf-E2.

   Evidence Biochemical binding assays, biophysical analyses, and site-directed mutagenesis of Pf-E2 and human/parasite SUMO

   PMID:35331687

   Open questions at the time

   • Functional consequence of the SUMO–E2 interaction on substrate conjugation not measured
   • Interaction shown in vitro only; not validated in parasite cells
   • Whether these interface differences can be exploited pharmacologically not tested

• The substrate repertoire, catalytic dynamics, and biological role of PF3D7_1033900 in parasite development and viability remain uncharacterized in the available corpus.
• No SUMO substrates of Pf-E2 identified
• No genetic knockdown/knockout phenotype reported
• No inhibitor targeting the parasite-specific interface demonstrated