The antioxidative effect of de novo generated vitamin B-6 in Plasmodium falciparum validated by protein interference

Author(s)

Knoeckel, Julia ; Mueller, Ingrid B. ; Butzloff, Sabine ; Bergmann, Baerbel ; Walter, Rolf D. ; Wrenger, Carsten

• Document type: Journal article
• Source: Biochemical Journal; v. 443, p. 9-pg., 2012-04-15.

Abstract

The malaria parasite Plasmodium falciparum is able to synthesize de novo PLP (pyridoxal 5'-phosphate), the active form of vitamin B-6. In the present study, we have shown that the de novo synthesized PLP is used by the parasite to detoxify O-1(2) (singlet molecular oxygen), a highly destructive reactive oxygen species arising from haemoglobin digestion. The formation of O-1(2) and the response of the parasite were monitored by live-cell fluorescence microscopy, by transcription analysis and by determination of PLP levels in the parasite. Pull-down experiments of transgenic parasites overexpressing the vitamin B-6-biosynthetic enzymes PfPdx1 and PfPdx2 clearly demonstrated an interaction of the two proteins in vivo which results in an elevated PLP level from 12.5 mu M in wild-type parasites to 36.6 mu M in the PfPdx1/PfPdx2-overexpressing cells and thus to a higher tolerance towards O-1(2). In contrast, by applying the dominant-negative effect on the cellular level using inactive mutants of PfPdx1 and PfPdx2, P. falciparum becomes susceptible to O-1(2). Our results demonstrate clearly the crucial role of vitamin B-6 biosynthesis in the detoxification of O-1(2) in P falciparum. Besides the known role of PLP as a cofactor of many essential enzymes, this second important task of the vitamin B-6 de novo synthesis as antioxidant emphasizes the high potential of this pathway as a target of new anti-malarial drugs. (AU)

• FAPESP's process: 09/54325-2 - Elucidation of vitamin B metabolism in the human malaria parasite Plasmodium falciparum and their validation as a target for chemotherapy
• Grantee: Carsten Wrenger
• Support Opportunities: Research Grants - Young Investigators Grants