Abstract 2337 A High Dynamic Range ChemoG2 Biosensor for Quantifying Free Nedd8 in Living Cells

The novel thioredoxin-related protein 1 (TrxL-1) of the malaria parasite Plasmodium exhibits redox activity.Thioredoxins (Trx) occupy central roles in the redox networks of organisms from all domains of life, including the protozoan parasite Plasmodium.Cellular redox signaling via these Trx-systems is often mediated through downstream transducer proteins that act as effectors or links to diverse cellular processes.Here we characterize a novel thioredoxin-like protein (TrxL-1) of the rodent malaria parasite Plasmodium berghei (PbTrxL-1).The pbtrxl-1 gene codes for a 208 amino acid protein with a central thioredoxin-domain that lacks a classic CXXC active site motif.Conservation of the trxL-1 gene seems to be restricted to the phylum apicomplexa.Quantitative real-time PCR analysis revealed that pbtrxl-1 is strongly and stage-specifically upregulated during P. berghei ookinete development.The deletion of the trxl-1 gene, using CRISPR/Cas9, revealed that trxl-1 is dispensable for the asexual development of Plasmodium in the host's red blood cells.The maturation of ookinetes, however, is significantly delayed and, in some cases, leads to severe malformation of the parasite.To better understand the biochemical properties of PbTrxL-1, we cloned, recombinantly expressed, and purified the full-length protein.In vitro redox assays revealed that PbTrxL-1 is readily reduced by the P. berghei thioredoxin system, suggesting a potential role as a redox effector or link in the cellular redox network.A potential association with the parasite's cytoskeleton will be discussed.