Flavonoids Target Multiple Enzymes from the Type II Fatty Acid Pathway of Plasmodium falciparum and Do Not Invoke Delayed Death Phenomenon

Planta Medica ◽  
2006 ◽  
Vol 72 (11) ◽  
Author(s):  
D Tasdemir ◽  
G Lack ◽  
R Brun ◽  
M Kaiser ◽  
P Rüedi ◽  
...  
PLoS Biology ◽  
2011 ◽  
Vol 9 (3) ◽  
pp. e1001030
Author(s):  
Richard Robinson

2017 ◽  
Vol 62 (1) ◽  
Author(s):  
Taher Uddin ◽  
Geoffrey Ian McFadden ◽  
Christopher Dean Goodman

ABSTRACTMalaria parasites contain a relict plastid, the apicoplast, which is considered an excellent drug target due to its bacterial-like ancestry. Numerous parasiticidals have been proposed to target the apicoplast, but few have had their actual targets substantiated. Isopentenyl pyrophosphate (IPP) production is the sole required function of the apicoplast in the blood stage of the parasite life cycle, and IPP supplementation rescues parasites from apicoplast-perturbing drugs. Hence, any drug that kills parasites when IPP is supplied in culture must have a nonapicoplast target. Here, we use IPP supplementation to discriminate whether 23 purported apicoplast-targeting drugs are on- or off-target. We demonstrate that a prokaryotic DNA replication inhibitor (ciprofloxacin), several prokaryotic translation inhibitors (chloramphenicol, doxycycline, tetracycline, clindamycin, azithromycin, erythromycin, and clarithromycin), a tRNA synthase inhibitor (mupirocin), and two IPP synthesis pathway inhibitors (fosmidomycin and FR900098) have apicoplast targets. Intriguingly, fosmidomycin and FR900098 leave the apicoplast intact, whereas the others eventually result in apicoplast loss. Actinonin, an inhibitor of bacterial posttranslational modification, does not produce a typical delayed-death response but is rescued with IPP, thereby confirming its apicoplast target. Parasites treated with putative apicoplast fatty acid pathway inhibitors could not be rescued, demonstrating that these drugs have their primary targets outside the apicoplast, which agrees with the dispensability of the apicoplast fatty acid synthesis pathways in the blood stage of malaria parasites. IPP supplementation provides a simple test of whether a compound has a target in the apicoplast and can be used to screen novel compounds for mode of action.


2004 ◽  
Vol 381 (3) ◽  
pp. 719-724 ◽  
Author(s):  
Mili KAPOOR ◽  
C. Chandramouli REDDY ◽  
M. V. KRISHNASASTRY ◽  
Namita SUROLIA ◽  
Avadhesha SUROLIA

Triclosan is a potent inhibitor of FabI (enoyl-ACP reductase, where ACP stands for acyl carrier protein), which catalyses the last step in a sequence of four reactions that is repeated many times with each elongation step in the type II fatty acid biosynthesis pathway. The malarial parasite Plasmodium falciparum also harbours the genes and is capable of synthesizing fatty acids by utilizing the enzymes of type II FAS (fatty acid synthase). The basic differences in the enzymes of type I FAS, present in humans, and type II FAS, present in Plasmodium, make the enzymes of this pathway a good target for antimalarials. The steady-state kinetics revealed time-dependent inhibition of FabI by triclosan, demonstrating that triclosan is a slow-tight-binding inhibitor of FabI. The inhibition followed a rapid equilibrium step to form a reversible enzyme–inhibitor complex (EI) that isomerizes to a second enzyme–inhibitor complex (EI*), which dissociates at a very slow rate. The rate constants for the isomerization of EI to EI* and the dissociation of EI* were 5.49×10−2 and 1×10−4 s−1 respectively. The Ki value for the formation of the EI complex was 53 nM and the overall inhibition constant Ki* was 96 pM. The results match well with the rate constants derived independently from fluorescence analysis of the interaction of FabI and triclosan, as well as those obtained by surface plasmon resonance studies [Kapoor, Mukhi, N. Surolia, Sugunda and A. Surolia (2004) Biochem. J. 381, 725–733].


2011 ◽  
Vol 85 (4) ◽  
pp. 721-732 ◽  
Author(s):  
Manuel Roqueta-Rivera ◽  
Timothy L. Abbott ◽  
Mayandi Sivaguru ◽  
Rex A. Hess ◽  
Manabu T. Nakamura

2014 ◽  
Vol 80 (23) ◽  
pp. 7283-7292 ◽  
Author(s):  
Junjun Wu ◽  
Oliver Yu ◽  
Guocheng Du ◽  
Jingwen Zhou ◽  
Jian Chen

ABSTRACTMalonyl coenzyme A (malonyl-CoA) is an important precursor for the synthesis of natural products, such as polyketides and flavonoids. The majority of this cofactor often is consumed for producing fatty acids and phospholipids, leaving only a small amount of cellular malonyl-CoA available for producing the target compound. The tuning of malonyl-CoA into heterologous pathways yields significant phenotypic effects, such as growth retardation and even cell death. In this study, fine-tuning of the fatty acid pathway inEscherichia coliwith antisense RNA (asRNA) to balance the demands on malonyl-CoA for target-product synthesis and cell health was proposed. To establish an efficient asRNA system, the relationship between sequence and function for asRNA was explored. It was demonstrated that the gene-silencing effect of asRNA could be tuned by directing asRNA to different positions in the 5′-UTR (untranslated region) of the target gene. Based on this principle, the activity of asRNA was quantitatively tailored to balance the need for malonyl-CoA in cell growth and the production of the main flavonoid precursor, (2S)-naringenin. Appropriate inhibitory efficiency of the anti-fabB/fabFasRNA improved the production titer by 431% (391 mg/liter). Therefore, the strategy presented in this study provided a useful tool for the fine-tuning of endogenous gene expression in bacteria.


2010 ◽  
Vol 58 (10) ◽  
pp. 6157-6165 ◽  
Author(s):  
Bo Zhang ◽  
Ji-yuan Shen ◽  
Wen-wen Wei ◽  
Wan-peng Xi ◽  
Chang-Jie Xu ◽  
...  

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