Structure Elucidation and Characterization of the Venus Kinase Receptors of a Philippine Isolate of Schistosoma japonicum

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Worldwide, millions of people suffer from the parasitic disease called schistosomiasis. This disease is caused by the digenetic trematode of the genus Schistosoma. The disease is endemic in the Philippines. Schistosomiasis is a parasitic disease caused by blood dwelling worms. This disease is spread by freshwater snails infected with the human infective stage of the parasite called schistosome cercariae. The disease is characterized by morbidities like inflammation of the liver and the spleen. Schistosomiasis is endemic in the Philippines. Due to its morbidities, economic loss amount to millions of Philippine Peso per year. Two and a half million people have active infections, posing 12 million individuals at risk of infection. In the Philippines, S. japonicum is the only causative agent of schistosomiasis. The disease is widespread in 12 Regions, corresponding to 28 Provinces. Schistosomiasis control program in the Philippines include mass drug administration. Endemic places with high disease prevalence rates are treated with a single drug, praziquantel. A single dose is given once annually or biannually. However, resistance to the drug poses legitimate fear. Under laboratory conditions, S. mansoni worms treated with subcurative drug concentration developed resistance against praziquantel. Moreover, in Senegal (1988), mass drug administration of praziquantel failed to meet the expected parasitological cure rate of 70-90%. The disease pathologies are caused by schistosome eggs deposited in different organs in the human host. Schistosome eggs are the causative agents of schistosomiasis. As such, interventions of schistosome egg production may lead to reduction of disease burden and transmission control. In recent years, the discovery of Venus Kinase Receptors (VKRs) in S. mansoni opened new directions in schistosomiasis research. It has been found that VKRs are directly involved in egg production. Thus, inhibition of VKR proteins can be exploited to develop anti-schistosomiasis therapeutics.In order to develop new drugs active against schistosome worms, molecular understanding of VKR proteins will be needed. This proposal aims to undertake this complex task by employing cutting edge science and technology in the field of proteomics, drug design and membrane protein crystallography. We will express and purify the recombinant form of VKR proteins in either E. coli, S. cerivisiae or Bacullovirus expression systems. We will employ both experimental and computational approches to charcaterize VKR proteins in terms of their dimerization potential, ligand binding, and inhibitor interactions. Important to VKR inhibitor development is high resolution structure of VKR proteins. We will attempt to crystallize VKR proteins with and without their putative liagnds and inhibitors. The VKR structure will be used to screen small molecule VKR inhibitors, and will be tested for binding to VKR proteins and phosphorylase activity.The impact of anti-schistosomiasis drug development takes years to deliver to end users. But, this proposal is a huge leap towards its realization. The immediate beneficiaries of study outcomes will be the academic groups, allowing them to access free data of the 3D structure of VKR proteins. With VKR coordinates available, simultaneous work on the development of anti-schistosomiasis drugs worldwide will be facilitated. Lead compounds identified in the study can be exploited by pharmaceutical companies to speed up delivery of impact to suffering individiduals due to schistosomiasis.