Fructose increases the resistance of Rhodobacter capsulatus to the toxic oxyanion tellurite through repression of acetate permease (ActP)

Abstract

The highly toxic oxyanion tellurite (TeO(3) (2-)) enters the cells of the facultative photosynthetic bacterium Rhodobacter capsulatus through an acetate permease. Here we show that actP gene expression is down-regulated by fructose and this in turn determines a strong decrease of tellurite uptake and a parallel increase in the cells resistance to the toxic metalloid (from a minimal inhibitory concentration of 8 μM up to 400 μM tellurite under aerobic growth conditions). This demonstrates that there exists a direct connection between the level of tellurite uptake and the sensitivity of the cells to the oxyanion.

Reduction of Gold (III) and Tellurium (IV) by Enterobacter cloacae MF01 Results in Nanostructure Formation Both in Aerobic and Anaerobic Conditions

“…After 15 min exposure to HAuCl 4 or K 2 TeO 3 , most part (90%) of the metal(loid) remains in the extracellular fraction. While tellurite entrance is mediated mainly by the phosphate transporter PitA and/or by the acetate transporter ActP (Borghese et al, 2011; Elías et al, 2012, 2015), that of gold would be mediated by sulfhydryl group-rich membrane proteins (Snyder et al, 1986). As mentioned, about 10% of the toxicants enter the cell, which could generate an adaptive response thus enabling it to better respond to toxicant-mediated damage in aerobic (gold) or anaerobic growth conditions (tellurite).…”

On the role of a specific insert in acetate permeases (ActP) for tellurite uptake in bacteria: Functional and structural studies

“…In R. capsulatus it has been shown that a mutant impaired in tellurite uptake became highly resistant to the oxyanion and the uptake defect was restored by the acetate permease actP2 gene [17], supporting an earlier observation indicating that acetate inhibits tellurite uptake in R. capsulatus cells, as both anions compete for the same permease [18]. This evidence led to the proposal that in R. capsulatus tellurite enters the cell mainly through the acetate transport system (RcActP2) [17,19]. Early work in E. coli cells [20] reported that phosphate transport mutants were characterized with higher resistance to TeO 3 2-and that the oxyanion was a potent inhibitor of A C C E P T E D M A N U S C R I P T which identifies in the homodimeric structure of ActP2 a signature of the strong tellurite uptake activity shown by this permease, namely a 15 amino acids insert that is missing in all ActP1 type permeases.…”

“…pRB71 (Km r ) is a pRB3 derivative carrying a translational fusion of the actP2 operon from R. capsulatus to the reporter gene lacZ [19]. pRK415 (Tc r ) is a broad-host-range cloning plasmid for…”

“…To test whether acetate permease ActP2 of R. capsulatus was expressed in a heterologous background, the plasmid pRB71 [19] carrying an actP2::lacZ fusion, was first transformed into E. coli HB101 and -galactosidase activity was analyzed under different conditions of growth. As shown in Fig.…”

Transports of acetate and haloacetate in Burkholderiaspecies MBA4 are operated by distinct systems

“…It is possible that acetate and propionate were transported by the same transport system but further confirmation is required as Candidatus Competibacter phosphatis appeared to have different transporters for the two solutes [21]. Another acetate permease, ActP of Rhodobacter capsulatus , was produced around 1.5 folds more in acetate- than in pyruvate-grown cells [22]. This indicated that the regulations of various acetate-transport systems in different bacteria are likely to be different and should be compared cautiously.…”