A single valine to leucine switch disrupts Plasmodium falciparum AP2-G DNA binding and reveals GDV1's role in ap2-g activation.

Sexual commitment in Plasmodium parasites is essential for malaria transmission, yet the signaling events initiating sexual conversion in only a subpopulation of parasites remain unclear. We discovered a single valine(V2163) to leucine(L2163) mutation in a transcription factor required for P. falciparum gametocytogenesis (AP2-G) that abrogates sexual differentiation. AP2-G.L2163 does not bind the ap2-g consensus motif, GnGTAC, or stimulate gene transcription, including autoregulation. The GDV1-dependent expression of AP2-G.L2163 demonstrates GDV1's critical role in the initial activation of the silent ap2-g locus in the absence of functional AP2-G. While AP2-G.V2163 is required for MSRP1 expression, providing a marker that discriminates early from late sexually committed schizonts. Together this work demonstrates that V2163 in AP2-G plays a critical role in DNA binding, highlighting the functional importance of this specific region for malaria transmission as well as the key role of GDV1 in the initial activation of ap2-g expression and induction of sexual differentiation.