Characterization of Plasmodium falciparum Pantothenate Kinase and Identification of Its Inhibitors From Natural Products

Abstract

Coenzyme A (CoA) is a well-known cofactor that plays an essential role in many metabolic reactions in all organisms. In Plasmodium falciparum, the most deadly among Plasmodium species that cause malaria, CoA and its biosynthetic pathway have been proven to be indispensable. The first and rate-limiting reaction in the CoA biosynthetic pathway is catalyzed by two putative pantothenate kinases (PfPanK1 and 2) in this parasite. Here we produced, purified, and biochemically characterized recombinant PfPanK1 for the first time. PfPanK1 showed activity using pantetheine besides pantothenate, as the primary substrate, indicating that CoA biosynthesis in the blood stage of P. falciparum can bypass pantothenate. We further developed a robust and reliable screening system to identify inhibitors using recombinant PfPanK1 and identified four PfPanK inhibitors from natural compounds.

Pantothenate and CoA biosynthesis in Apicomplexa and their promise as antiparasitic drug targets

“…Studies in rodent malaria parasites have highlighted that single-copy PPCS and PPCDC are also dispensable [ 21 , 50 ]. The ability of PanK to phosphorylate pantetheine [ 61 ] points toward a possible salvage of pantetheine for CoA synthesis ( Fig 1 ), similar to observations in some bacteria [ 62 ], potentially rendering PPCS and PPCDC dispensable. Nevertheless, the presence of pantetheine-hydrolyzing enzymes, pantetheinases (vanins), in the serum possibly limits the amount of freely available pantetheine.…”

A novel heteromeric pantothenate kinase complex in apicomplexan parasites

“…gondii , coupled with the intense investigation of this pathway as a drug target in P . falciparum [ 27 , 39 – 41 , 52 – 67 ], suggests that further characterisation of Tg PanK, and the CoA biosynthesis pathway in T . gondii , could yield novel drug targets for chemotherapy.…”

“…There have been several attempts by us [unpublished] and others [37][38][39][40][41] to express a functional PfPanK1. Whilst the protein has been successfully expressed in soluble form using various heterologous expression systems (Escherichia coli, insect cells, Saccharomyces cerevisiae), until recently [41], no study had reported PanK activity from the heterologously-expressed and purified protein. Nurkanto et al [41] have recently reported the functional expression of PfPanK1 in E. coli.…”

“…Whilst the protein has been successfully expressed in soluble form using various heterologous expression systems (Escherichia coli, insect cells, Saccharomyces cerevisiae), until recently [41], no study had reported PanK activity from the heterologously-expressed and purified protein. Nurkanto et al [41] have recently reported the functional expression of PfPanK1 in E. coli. The expressed protein was initially insoluble but was solubilised using high concentrations of trehalose.…”

“…Our data indicate that T. gondii parasites are unable to scavenge sufficient downstream intermediates in the CoA biosynthesis pathway, including CoA, from their host cells, for their survival, and therefore must maintain their own active CoA biosynthesis pathway. The requirement for CoA biosynthesis in T. gondii, coupled with the intense investigation of this pathway as a drug target in P. falciparum [27,[39][40][41][52][53][54][55][56][57][58][59][60][61][62][63][64][65][66][67], suggests that further characterisation of TgPanK, and the CoA biosynthesis pathway in T. gondii, could yield novel drug targets for chemotherapy.…”