Nanopipettes were used for real-time investigation into actin dynamics and drug binding at single-molecule resolution, showing promise for a better understanding of the mechanism of protein–protein interactions and drug discovery.

Polymerization of the cytosolic protein actin is critical to cell movement and host-cell invasion by the malaria parasite, Plasmodium falciparum. Any disruption to actin polymerization dynamics will render the parasite incapable of invading a host cell and thereby unable to cause infection. Here, we explore the potential of using truncated latrunculins as potential chemotherapeutics for the treatment of malaria. Exploration of the binding interactions of the natural actin inhibitor latrunculins, with actin revealed how a truncated core of the inhibitor could retain its key interaction features with actin. This truncated core was synthesised and subjected to preliminary structure-activity relationship studies to generate a focused set of analogues. Biochemical analyses of these analogues demonstrate their 6-fold increased activity compared with latrunculin B against Plasmodium falciparum and a 16-fold improved selectivity ex vivo. These data establish the latrunculin core as a potential focus for future structure-based drug design of chemotherapeutics against malaria.

14Advances in synthetic biology have enabled production of a variety of compounds using 15 bacteria as a vehicle for complex compound biosynthesis. Violacein, a naturally occurring 16 indole pigment with antibiotic properties, can be biosynthetically engineered in Escherichia 17 coli expressing its non-native synthesis pathway. To explore whether this synthetic 18 biosynthesis platform could be used for drug discovery, here we have screened bacterially-19 derived violacein against the main causative agent of human malaria, Plasmodium 20 falciparum. We show the antiparasitic activity of bacterially-derived violacein against the P. 21 falciparum 3D7 laboratory reference strain as well as drug-sensitive and resistant patient 22 33 KEYWORDS 34 Violacein; drug discovery; synthetic biology; antimalarial 35 36 on July 8, 2020 by guest http://aac.asm.org/ Downloaded from

Complementation of a conditional KO of actin-depolymerizing factor (ADF) in Toxoplasma gondii demonstrates that ADF-dependent actin filament disassembly is essential for parasite development but not for cell motility. Furthermore, trans-genera complementation highlights genus-specific coevolution between ADF proteins and their native actins.