Synergistic interaction of glyceraldehydes‐3‐phosphate dehydrogenase and ArsJ, a novel organoarsenical efflux permease, confers arsenate resistance

Abstract

Summary Microbial biotransformations are major contributors to the arsenic biogeocycle. In parallel with transformations of inorganic arsenic, organoarsenicals pathways have recently been recognized as important components of global cycling of arsenic. The well-characterized pathway of resistance to arsenate is reduction coupled to arsenite efflux. Here, we describe a new pathway of arsenate resistance involving biosynthesis and extrusion of an unusual pentavalent organoarsenical. A number of arsenic resistance (ars) operons have two genes of unknown function that are linked in these operons. One, gapdh, encodes the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase. The other, arsJ, encodes a major facilitator superfamily (MFS) protein. The two genes were cloned from the chromosome of Pseudomonas aeruginosa. When expressed together, but not alone, in Escherichia coli, gapdh and arsJ specifically conferred resistance to arsenate and decreased accumulation of As(V). Everted membrane vesicles from cells expressing arsJ accumulated As(V) in the presence of purified GAPDH, D-glceraldehylde 3-phosphate (G3P) and NAD+. GAPDH forms the unstable organoarsenical 1-arseno-3-phosphoglycerate (1As3PGA). We propose that ArsJ is an efflux permease that extrudes 1As3PGA from cells, where it rapidly dissociates into As(V) and 3-phosphoglycerate (3PGA), creating a novel pathway of arsenate resistance.

Phosphate starvation response controls genes required to synthesize the phosphate analog arsenate

“…Chen et al . () regard it as an arsenate‐specific resistance mechanism, but nevertheless illustrates how arsenate esters may exhibit sufficient stability so as to participate in metabolism in a measurable way and perform in a manner consistent with expectations – in this context, arsenic resistance.…”

“…As currently understood, arsenic incorporation into biomass should not involve arsenate esters in key structures (e.g., nucleic acids or ATP metabolism) because the bond is viewed to be too unstable (Rosen et al, 2011). However, we draw attention to a recent study by the Rosen group that examined the functional importance of a gene encoding a glyceraldehyde-3phosphate dehydrogenase (GAPDH) that is found in many ars operons and up-regulated in response to arsenic exposure (Chen et al, 2016). The GAPDH was shown to incorporate arsenate into glyceraldehyde-3-phosphate, generating 1-arseno-3-phosphoglycerate that is an export transport substrate for ArsJ.…”

Organoarsenical Biotransformations by Shewanella putrefaciens

“…14 The product of the gapdh gene, glyceraldehydes-3-phosphate dehydrogenase arsenylates glyceraldehydes-3-phosphate to 1-arseno-3-phosphoglycerate, the substrate of the arsJ gene product, the ArsJ efflux permease. 30 Other known organoarsenical biotransformation genes are absent from the genome of S. putrefaciens 200. These include a gene for the ArsM As(III) S-adenosylmethionine methyltransferase, 25 and S. putrefaciens 200 did not methylate As(III) (data not shown).…”

Arsenic and the gastrointestinal tract microbiome

“…Many ars operons contain genes encoding glyceraldehyde‐3‐phosphate dehydrogenase (GAPDH) and arsJ , with both up‐regulated in response to As(III). In Pseudomonas aeruginosa (Chen et al ., ) and Halomonas sp. (Wu et al ., ), GAPDH incorporates As(V) into glyceraldehyde‐3‐phosphate, generating 1‐arseno‐3‐phosphoglycerate that is a transport substrate for the exporter ArsJ (Figs B and ).…”