Copper detoxification machinery of the brain-eating amoeba Naegleria fowleri involves copper-translocating ATPase and the antioxidant system

Abstract

Copper is a trace metal that is necessary for all organisms but toxic when present in excess. Different mechanisms to avoid copper toxicity have been reported to date in pathogenic organisms such as Cryptococcus neoformans and Candida albicans . However, little if anything is known about pathogenic protozoans despite their importance in human and veterinary medicine. Naegleria fowleri is a free-living amoeba that occurs naturally in warm fresh water and can cause a rapid and deadly brain infection called primary amoebic meningoencephalitis (PAM). Here, we describe the mechanisms employed by N. fowleri to tolerate high copper concentrations, which include various strategies such as copper efflux mediated by a copper-translocating ATPase and upregulation of the expression of antioxidant enzymes and obscure hemerythrin-like and protoglobin-like proteins. The combination of different mechanisms efficiently protects the cell and ensures its high copper tolerance, which can be advantageous both in the natural environment and in the host. Nevertheless, we demonstrate that copper ionophores are potent antiamoebic agents; thus, copper metabolism may be considered a therapeutic target.

A novel leishmanial copper P-type ATPase plays a vital role in parasite infection and intracellular survival

“…However, given that the internal Cu in the parasite is maintained at an extremely low level (∼3–4 ppb as measured in promastigotes using inductively coupled plasma optical emission spectrometry [ICP–OES]), the survivability trend indicated that L. major exhibits Cu resistance or tolerance to an appreciable extent. Internal Cu content of L. major is relatively low as compared with other pathogenic protozoa like Naegleria fowleri whose internal Cu amounts to about 84.1 ppb ( 29 ). We argue that an efficient Cu handling machinery must be present in the parasite that confers its survivability in elevated nonphysiological Cu.…”

“…Although the role of iron has been extensively studied in kinetoplastid parasites, there have been limited efforts to understand the role of Cu in their survival or pathogenicity in this order as well as protozoal parasite as a whole. Pathogenic protozoa like N. fowleri and Plasmodium falciparum use their Cu-ATPase to detoxify Cu ( 29 , 48 ). C. albicans also employ this transporter to maintain Cu homeostasis ( 49 ).…”

Copper Metabolism in Naegleria gruberi and Its Deadly Relative Naegleria fowleri

“…To ensure sufficient copper status, the cells cultivated in presence of 25 µM Cu 2 SO 4 were used as a control sample for both proteomic analyses. This concentration was used based on our previous work where we elucidated the IC50 of copper being 1 mM for N. gruberi and as high as 1.6 mM for N. fowleri ( Grechnikova et al, 2020 ).…”

“…In a recent study, we described how N. fowleri handles the toxic properties of copper and identified the key protein of the copper detoxification pathway, a copper-translocating ATPase ( Grechnikova et al, 2020 ). In the present study, we focused on other aspects of copper metabolism and aimed to elucidate the metabolic adaptations of the free-living unicellular organism N. gruberi and its pathogenic relative N. fowleri to low copper availability.…”

“…Both amoebas were recently shown to be able to adjust their metabolism to reflect iron availability, downregulating nonessential and predominantly cytosolic iron-dependent pathways and utilizing available iron primarily in mitochondria to maintain essential energy metabolism ( Mach et al, 2018 ; Arbon et al, 2020 ). In our previous study, we described how N. fowler i handles copper toxicity by upregulating a specific copper-exporting ATPase, a key protein of the copper detoxification pathway ( Grechnikova et al, 2020 ). Recent study has found that Cryptococcus neoformans is able to sense different Cu environment during infection: high Cu in lungs and low Cu level in brain and is able to adapt its Cu acquisition in these different niches ( Sun et al, 2014 ).…”