PF3D7_1357000

PF3D7_1357000 encodes elongation factor 1-alpha (EF-1alpha), which in P. falciparum, P. knowlesi, and P. berghei is present as two identical, simultaneously expressed gene copies arranged head-to-head, an organization consistent with a gene dosage function during erythrocytic development (PMID:9719506). Beyond this genomic and expression characterization, the corpus provides two additional context-specific observations. In chloroquine-treated P. falciparum-infected erythrocytes, ferriprotoporphyrin IX (FPIX) accumulates in parasite cytosol and binds EF-1alpha, though the functional consequence of this binding is not established (PMID:12669348). In P. berghei NK65, EF-1alpha is secreted via parasite-derived extracellular vesicles and is required for the vesicles' immunosuppressive activity: EVs lacking EF-1alpha fail to inhibit CD4+ T cell proliferation and no longer dephosphorylate the T cell receptor signalling molecules PLCγ1, Akt, and ERK (PMID:30835870). No direct enzymatic or translational-mechanism data for PF3D7_1357000 itself has been characterized in the available corpus.

1. 1998 Medium

   It was unknown how EF-1alpha is encoded in Plasmodium; genomic characterization established that the gene exists as two identical, co-expressed copies in a head-to-head arrangement, implying a gene dosage rather than functional-specialization role.

   Evidence Genomic Southern blotting, two-copy sequence analysis, stage-specific expression profiling, and codon-usage analysis across three Plasmodium species

   PMID:9719506

   Open questions at the time

   • The proposed bidirectional/dual promoter was inferred but not tested by reporter assay
   • No direct demonstration of translational elongation activity for the encoded protein
   • Functional necessity of the two-copy arrangement was not tested genetically
2. 2003 Low

   To identify parasite targets of heme accumulation during chloroquine action, affinity extraction revealed that FPIX binds EF-1alpha in the parasite cytosol, placing EF-1alpha among the cytosolic FPIX-binding proteins.

   Evidence FPIX-affinity extraction from P. falciparum parasite cytosol followed by protein sequencing/identification

   PMID:12669348

   Open questions at the time

   • Single pulldown/affinity method from one lab, no reciprocal or in vitro binding validation
   • The functional consequence of FPIX binding to EF-1alpha was not established
   • Binding specificity relative to other cytosolic proteins not quantified
3. 2019 Medium

   It was unknown whether EF-1alpha has a role beyond translation; genetic knockout showed that EF-1alpha carried by parasite extracellular vesicles is required for host immunosuppression, revealing a moonlighting function in dampening T cell receptor signalling.

   Evidence EF-1alpha knockout in P. berghei NK65, EV isolation, in vitro CD4+ T cell proliferation assay, in vivo delayed-type hypersensitivity assay, and phosphorylation analysis of PLCγ1/Akt/ERK

   PMID:30835870

   Open questions at the time

   • The molecular mechanism by which EF-1alpha drives dephosphorylation of TCR signalling molecules is not defined
   • Shown in P. berghei NK65; not demonstrated for the P. falciparum PF3D7_1357000 protein
   • How EF-1alpha is loaded into and secreted by extracellular vesicles is unknown

• It remains unknown whether the canonical translational-elongation activity of PF3D7_1357000 is essential in P. falciparum and how its moonlighting immunosuppressive role and FPIX binding relate mechanistically to its core function.
• No genetic essentiality or translational-activity data for PF3D7_1357000 in P. falciparum
• No structural or biochemical mechanism linking FPIX binding to any functional outcome
• The immunosuppressive phenotype has only been shown for the P. berghei ortholog