New enzymatic pathways for the reduction of reactive oxygen species in Entamoeba histolytica.
BACKGROUND
Entamoeba histolytica, an intestinal parasite that is the causative agent of amoebiasis, is exposed to elevated amounts of highly toxic reactive oxygen and nitrogen species during tissue invasion. A flavodiiron protein and a rubrerythrin have been characterized in this human pathogen, although their physiological reductants have not been identified.


METHODS
The present work deals with biochemical studies performed to reach a better understanding of the kinetic and structural properties of rubredoxin reductase and two ferredoxins from E. histolytica.


RESULTS
We complemented the characterization of two different metabolic pathways for O2 and H2O2 detoxification in E. histolytica. We characterized a novel amoebic protein with rubredoxin reductase activity that is able to catalyze the NAD(P)H-dependent reduction of heterologous rubredoxins, amoebic rubrerythrin and flavodiiron protein but not ferredoxins. In addition, the protein exhibited an NAD(P)H oxidase activity, which generates hydrogen peroxide from molecular oxygen. We describe how different ferredoxins were also efficient reducing substrates for both flavodiiron protein and rubrerythrin.


CONCLUSIONS
The enzymatic systems herein characterized could contribute to the in vivo detoxification of O2 and H2O2, playing a key role for the parasite defense against reactive oxidant species.


CONCLUSIONS
To the best of our knowledge this is the first characterization of a eukaryotic rubredoxin reductase, including a novel kinetic study on ferredoxin-dependent reduction of flavodiiron and rubrerythrin proteins.
Instituto de Agrobiotecnología del Litoral-Facultad de Bioquímica y Ciencias Biológicas (CONICET-Universidad Nacional del Litoral), Santa Fe, Argentina.
Matías S
MS
Cabeza
Instituto de Agrobiotecnología del Litoral-Facultad de Bioquímica y Ciencias Biológicas (CONICET-Universidad Nacional del Litoral), Santa Fe, Argentina.
Sergio A
SA
Guerrero
Instituto de Agrobiotecnología del Litoral-Facultad de Bioquímica y Ciencias Biológicas (CONICET-Universidad Nacional del Litoral), Santa Fe, Argentina.
Alberto A
AA
Iglesias
Instituto de Agrobiotecnología del Litoral-Facultad de Bioquímica y Ciencias Biológicas (CONICET-Universidad Nacional del Litoral), Santa Fe, Argentina. Electronic address: darias@fbcb.unl.edu.ar.
Diego G
DG
Arias
D003001:Cloning, Molecular; D004748:Entamoeba histolytica / Q000201:enzymology* / Q000235:genetics; D006422:Hemerythrin / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism; D007700:Kinetics; D009247:NADH, NADPH Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D009249:NADP / Q000378:metabolism; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D012416:Rubredoxins / Q000378:metabolism
D006422:Hemerythrin; D015800:Protozoan Proteins; D017382:Reactive Oxygen Species; D011994:Recombinant Proteins; D012416:Rubredoxins; C055857:rubrerythrins; D009249:NADP; D006861:Hydrogen Peroxide; C023091:rubredoxin-NAD+ reductase; D009247:NADH, NADPH Oxidoreductases; D010100:Oxygen
Antioxidant; Entamoeba; Ferredoxin; Flavodiiron-protein; Rubredoxin; Rubrerythrin