Efflux Permease CgAcr3-1 of Corynebacterium glutamicum Is an Arsenite-specific Antiporter

Abstract

Background: CgAcr3-1 is an arsenite permease that catalyzes As(III) efflux from Corynebacterium glutamicum. Results: CgAcr3-1 is an As(III)-specific H ϩ /As(OH) 3 antiporter coupled to the proton motive force.

Pathways of Arsenic Uptake and Efflux

“…However, neither dissipating the positive interior Δψ alone nor the acid interior ΔpH alone had a significant effect on NADH-driven accumulation of As(III) in everted vesicles, indicating that either individual component of the electrochemical proton gradient, Δψ or ΔpH, is capable of energizing As(III) transport via CgAcr3-1. These results demonstrate that Acr3 is an electrophoretic metalloid–proton exchanger with As(OH) 3 /H + antiporter activity (Villadangos et al, 2012). …”

“…Recently, ScAcr3p has been suggested to transport Sb(III) in vivo as well (Maciaszczyk-Dziubinska et al, 2012), and yeast plasma membrane vesicles accumulate both As(III) and Sb(III) by exchange with protons (Maciaszczyk-Dziubinska et al, 2012). However, other data indicating that Sb(III) is not transported in yeast plasma membrane vesicles are not in agreement with that conclusion (Ghosh et al, 1999), and bacterial Acr3 orthologues appear to be specific for As(III) and do not transport Sb(III) (Fu et al, 2009; Villadangos et al, 2012). …”

Genome comparison of two Exiguobacterium strains from high altitude andean lakes with different arsenic resistance: identification and 3D modeling of the Acr3 efflux pump

“…Members of the Acr3 family are found in bacteria, archaea and fungi (Rosen, 1999;Wysocki et al, 2003) and in environmental studies acr3 genes seem to be very widespread among arsenic resistant bacteria, even more than arsB genes (Achour et al, 2007;Cai et al, 2009). Nevertheless, Acr3 proteins have been functionally characterized only in a few species including Bacillus subtilis, Synechocystis sp., Corynebacterium glutamicum and Saccharomyces cerevisiae (López-Maury et al, 2003;Aaltonen and Silow, 2008;Fu et al, 2009;MaciaszczykDziubinska et al, 2011;Villadangos et al, 2012), the last being the best studied microorganism where Acr3 acts as a metalloid/H(+) antiporter for arsenite and antimonite. Poirel et al suggest that arsB and acr3, arsenite transporter genes, are appropriate biomarkers of arsenic stress that may be suitable for further exploring the adaptive response of bacterial communities to arsenic in contaminated environments (Poirel et al, 2013).…”

Mechanisms of Arsenic Detoxification and Resistance

“…Acr3 has been demonstrated to be an antiporter that catalyzes arsenite-proton exchange (Villadangos et al, 2012). Bacterial Acr3 proteins appear to be specific for As(III) and do not transport Sb(III) (Fu et al, 2009;Villadangos et al, 2012). On the other hand, yeast Acr3p has been suggested to transport both As(III) and Sb(III) (Maciaszczyk-Dziubinska et al, 2010).…”

“…The membrane topology of Alkaliphilus metalliredigens AmAcr3-1 shows that, it has ten transmembrane spanning segments, with the N-and C-termini localized in the cytosol (Fu et al, 2009). Acr3 has been demonstrated to be an antiporter that catalyzes arsenite-proton exchange (Villadangos et al, 2012). Bacterial Acr3 proteins appear to be specific for As(III) and do not transport Sb(III) (Fu et al, 2009;Villadangos et al, 2012).…”