Biosynthesis of isoprenoids in Plasmodium falciparum. Evaluation of possible targets to obtain new anti-malarial drugs.

• Grant number: 24/09997-2
• Support Opportunities: Regular Research Grants
• Start date: April 01, 2025
• End date: March 31, 2027
• Field of knowledge: Biological Sciences - Parasitology - Protozoology of Parasites
• Principal Investigator: Alejandro Miguel Katzin
• Grantee: Alejandro Miguel Katzin
• Host Institution: Instituto de Ciências Biomédicas (ICB). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated researchers: Giuseppe Palmisano

Abstract

A fact that favors the increase in morbidity and mortality from malaria in the world is the resistance to chemotherapy drugs that the parasite presents. Therefore, it is necessary to identify new specific potential targets in the parasite, in order to carry out rational planning. The present project is intended to complement the studies that have already been developed in our laboratory for more than 35 years on the biosynthesis of isoprenoids in the intraerythrocytic stages of Plasmodium falciparum. All isoprenoids derive from a common precursor, isopentenyl pyrophosphate and its isomer dimethylallyl pyrophosphate, with prenylsynthase enzymes being responsible for catalyzing the sequential condensation of isoprene units. Several intermediates and end products of this pathway have been identified in the parasite in our laboratory, which lead us to conclude that it is different from the vertebrate host. Therefore, we can identify potential targets for evaluating antimalarial drugs. In this line of research, we continued this project, identifying other products derived from the biosynthesis of isoprenoids in the intraerythrocytic forms of P. falciparum, the cytokinins. Cytokinins are substances chemically related to the same biosynthesis routes as terpenoids, carotenoids, gibberellins, and abscisic acid. All of these substances are derived from dimethylallyl pyrophosphate, using the 2C-methyl-D-erythritol-4-phosphate (MEP) pathway as a source of precursors. In our laboratory, different cytokinins were identified in the intraerythrocytic stages of P. falciparum, through metabolic markings and we determined that the cytokinins isopentenyladenosine and trans-zeatin are capable of stimulating the growth of the parasite. To confirm the presence of these cytokinins in the intraerythrocytic stages of P. falciparum, we must identify them by mass spectrometry (LC-MS), and quantify the growth of the parasites in their presence.The ubiquinones (UQ 8-9), described in P. falciparum, have a structure composed of an isoprenic chain, originating from the MEP pathway, and an aromatic group, originating from the shikimate pathway, both absent in mammalian cells. In our laboratory, the isoprenic chains, and the shikimate and chorismate precursors of the aromatic ring of ubiquinones were identified by metabolic markings. The presence of these intermediates must be confirmed by mass spectrometry in the intraerythrocytic stages of P. falciparum. Once the shikimate biosynthesis pathway is confirmed, different inhibitors derived from 5-caffeoylquinic acid will be evaluated. The inhibition of specific enzymes of the shikimate pathway, as well as the enzyme 4-hydroxybenzoate polyprenyltransferase, can lead to a deficiency in the biosynthesis of prenylquinones essential for the parasite's respiratory chain.In our laboratory, several enzymes related to isoprenoid biosynthesis have already been identified and we have recently identified the polyprenol kinase that has the capacity to phosphorylate 20 C polyprenols and we intend to evaluate different inhibitors of this enzyme. The identification and characterization of polyprenol kinase inhibitors, involved in the use of exogenous and endogenous prenols by the parasite, may reveal new opportunities for the development of combined therapies. Synthetic terpenes, such as geranylgeranylacetone (GGA), have antimalarial potential by interfering with the parasite's prenylation processes and the use of exogenous isoprenoids. Exploration of these compounds could lead to the development of new classes of antimalarial drugs with innovative modes of action. Additionally, PolK seems to be involved in the regulation of carbon metabolism and glycolysis, another aspect that this proposal aims to evaluate. (AU)