The hypusine pathway in Ixodes ricinus: molecular cloning and validation of deoxyhypusine synthase as a novel target for drug discovery to treat and prevent vector borne diseases.

Ticks are a group of arthropod vectors transmitting a variety of human pathogens, like Borrelia and the tick-borne Encephalitis virus. In Europe, Ixodes is the most important tick due to its wide distribution. Since the 20th century, Ixodes has significantly spread due to changes in biodiversity. Thus, there is an urgent need to decrease tick ubiquity in the environment to control tick-borne diseases. Deoxyhypusine Synthase (DHS) catalyzes the first step in the post translational modification (PTM) of the amino acid hypusine in eukaryotic initiation factor (eIF5A). Modified eIF5A plays a crucial role in cell proliferation of different parasites. Therefore, we cloned a putative DHS locus of 1098 bp from Ixodes by a reverse genetic approach from total RNA of salivary glands and expressed the protein in E. coli. Ixodes DHS encodes an ORF of 365 amino acids and is commonly spread in different Ixodes (98.36%) and Rhipicephalus species (99%), and fruit flies (70.92%). The expressed DHS protein has a molecular weight of 40.88 kDa and a determined pI of 5.12. In an activity assay the enzyme shows moderate activity. In the future, we intend to perform virtual docking experiments once a 3D structure of Ixodes ricinus has been resolved to evaluate DHS as a novel target and to discover potent inhibitors to define its role in infection.