Selleck BYL719 Bacteria have developed different strategies to transform arsenic including arsenite oxidation, cytoplasmic arsenate reduction, find more respiratory arsenate reduction, and arsenite methylation [3]. The primary role of some of these transformations is to cope with arsenic toxiCity. Arsenite-oxidizing bacteria oxidize arsenite [As(III)] to arsenate [As(V)] which in many cases is considered primarily a detoxification metabolism since As(V) is much less toxic than As(III). In addition,

As(V) is negatively charged and can be easily adsorbed, thus such bacteria have been used in batch reactors together with immobilizing material for removing arsenic from waste water [4, 5]. As(III) oxidation has been identified in various bacteria including Pseudomonas [6], Alcaligenes [7], Thiomonas [8], Herminiimonas https://www.selleckchem.com/products/qnz-evp4593.html [9], Agrobacterium [10], and Thermus [11]. Some of these bacteria were

able to use As(III) as the sole electron donor and grew as lithotrophs. However, characterized heterotrophic arsenite-oxidizing bacteria have not been shown to gain energy through arsenite oxidation and probably use As(III) oxidation as a detoxification mechanism. Arsenite oxidation was catalyzed by a periplasmic arsenite oxidase. This enzyme contains two subunits encoded by the genes aoxA/aroB/asoB (small Fe-S Rieske subunit) and aoxB/aroA/asoA (large Mo-pterin subunit) respectively [12–14]. Recently aoxB-like sequences have been widely found in different arsenic contaminated soil and water systems [15]. Two families of arsenite transport proteins responsible for As(III) extrusion, ArsB and Acr3p, have been shown to confer arsenic resistance [12, 16, 17]. The founding member of the ArsB family, ArsB from E. coli, has been extensively characterized and shown to be a 45 kDa, inner membrane protein with 12 transmembrane helices [18, 19]. Either ArsB alone or in association with ArsA catalyzes the extrusion of arsenite and antimonite from cells [20]. In most cases, arsB is co-transcribed with arsC

encoding an arsenate reductase. It has been suggested that evolution and horizontal gene transfer (HGT) of both the ArsB and the ArsC family may have happened simultaneously in microbial evolution [12]. In many cases, As(III) is taken up by aquaglyceroporins [21] and extruded by ArsB [22]. Florfenicol Members of Acr3p transporters showed a function similar to ArsB, but the two proteins have no significant sequence similarity. Even though Acr3p is much less characterized, it has been reported to be present in more phylogenetically distant species than ArsB. Acr3p could be divided into two subfamilies, Acr3(1)p and Acr3(2)p, based on their phylogenetic dissimilarities [16, 23]. Acr3p appeared to be more specific and transported only arsenite but not antimonite [24, 25], except that Acr3p of Synechocystis was able to transport both arsenite and antimonite [26].