Glutathione Reductase-Mediated Synthesis of Tellurium-Containing Nanostructures Exhibiting Antibacterial Properties

Abstract

Tellurium, a metalloid belonging to group 16 of the periodic table, displays very interesting physical and chemical properties and lately has attracted significant attention for its use in nanotechnology. In this context, the use of microorganisms for synthesizing nanostructures emerges as an eco-friendly and exciting approach compared to their chemical synthesis. To generate Tecontaining nanostructures, bacteria enzymatically reduce tellurite to elemental tellurium. In this work, using a classic biochemical approach, we looked for a novel tellurite reductase from the Antarctic bacterium Pseudomonas sp. strain BNF22 and used it to generate tellurium-containing nanostructures. A new tellurite reductase was identified as glutathione reductase, which was subsequently overproduced in Escherichia coli. The characterization of this enzyme showed that it is an NADPH-dependent tellurite reductase, with optimum reducing activity at 30°C and pH 9.0. Finally, the enzyme was able to generate Te-containing nanostructures, about 68 nm in size, which exhibit interesting antibacterial properties against E. coli, with no apparent cytotoxicity against eukaryotic cells.

Escherichia coli 6-phosphogluconate dehydrogenase aids in tellurite resistance by reducing the toxicant in a NADPH-dependent manner

“…These activities, that include catalase, dihydrolipoamide dehydrogenase, isocitrate dehydrogenase and other enzymes displaying a branch NAD(P)H-dependent telluritereducing activity, are generically known as tellurite reductases (Chiong et al, 1988;Moscoso et al, 1998;Calderón et al, 2006;Castro et al, 2008;Reinoso et al, 2013;Pugin et al, 2014).…”

“…Construction of growth curves and minimal inhibitory concentration (MIC) and growth inhibition zones determination were carried out as described previously Castro et al, 2008Castro et al, , 2009Pugin et al, 2014).…”

“…It has been observed that this toxicant can be enzymatically reduced to elemental tellurium (Te 0 ) in a cofactor-dependent manner in different microorganisms (Chiong et al, 1988;Moscoso et al, 1998;Calderón et al, 2006;Castro et al, 2008;Pugin et al, 2014). NADPH levels can also be affected by non-enzymatic tellurite reduction by glutathione (GSH) or other cell reducing agents (Turner et al, 1999(Turner et al, , 2001.…”

Nanopartículas Sintetizadas por Bacterias Antárticas y sus Posibles Mecanismos de Síntesis

“…Algunas adaptaciones enzimáticas y no enzimáticas descritas en bacterias antárticas son glutatión s-transferasa (Shi et al, 2014), glutatión reductasa (Pugin et al, 2014), tioredoxina (Falasca et al, 2012) catalasas (Tribelli et al, 2012), super óxido dismutasas (Zheng et al, 2006), carotenoides (Dieser et al, 2010) y óxido reductasas (Madonna et al, 2006).…”

The Metalloid Reductase of Pseudomonas Moravenis Stanleyae Conveys Nanoparticle Mediated Metalloid Tolerance

“…15 This class of enzymes have demonstrated their ability to reduce a variety of metal ions to zerovalent forms including Se, Hg, Te, Fe, Cr, and U. [16][17][18][19] GSHR is reported to reduce Au(III) to zerovalent form as well. 20 Thus, the class of pyridine nucleoside dependent oxidoreductases may represent an evolutionarily adaptable platform of inorganic ion reductases, with modifications to the enzyme altering metal ion selectivity.…”