Function and Regulation of Acid Resistance Antiporters

Abstract

Bacterial pathogens are a major cause of foodborne diseases and food poisoning. To cope with the acid conditions encountered in different environments such as in fermented food or in the gastric compartment, neutralophilic bacteria have developed several adaptive mechanisms. One of those mechanisms, the amino acid dependent system, consumes intracellular protons in biochemical reactions. It involves an antiporter that facilitates the exchange of external substrate amino acid for internal product and a cytoplasmic decarboxylase that catalyzes a proton-consuming decarboxylation of the substrate. So far, four acid resistance antiporters have been discovered, namely the glutamate-γ-aminobutyric acid antiporter GadC, the arginine-agmatine antiporter AdiC, the lysine-cadaverine antiporter CadB, and the ornithine-putrescine antiporter PotE. The 3D structures of AdiC and GadC, reveal an inverted-repeat fold of two times 5 transmembrane helices, typical of the amino acid-polyamine-organocation (APC) superfamily of transporters. This review summarizes our current knowledge on the transport mechanism, the pH regulation and the selectivity of these four acid resistance antiporters. It also highlights that AdiC is a paradigm for eukaryotic amino acid transporters of the APC superfamily as structural models of several of these transporters built using AdiC structures were exploited to unveil their mechanisms of amino acid recognition and translocation.

Screening of gamma-aminobutyric acid-producing lactic acid bacteria and the characteristic of glutamate decarboxylase from Levilactobacillus brevis F109-MD3 isolated from kimchi

“…Bacteria employ multiple strategies for maintaining neutral cytoplasmic pH (pHi) despite an acidic external environment. One of the most important strategies depends on amino acid decarboxylationantiporter reactions (Krammer & Prévost, 2019). Due to that, the sour taste might be alleviated in case of LAB fermentation during the food processing, and it might be useful for the sensory of functional food or food additives.…”

Bacterial infection reinforces host metabolic flux from arginine to spermine for NLRP3 inflammasome evasion

“…Arginine in bacteria can be catalyzed to amino acids or polyamines, including agmatine, spermidine, and putrescine (Cunin et al, 1986;Lu, 2006). Moreover, putrescine can be exported out of bacteria through the Cell Reports 34, 108832, March 9, 2021 9 Article ll OPEN ACCESS potE exchanger, and spermidine can be imported preferentially through the potABCD system (Igarashi and Kashiwagi, 2010;Krammer and Pré vost, 2019). For example, during Shigella infection in macrophages, a high level of spermidine can stimulate expression of OxyR to promote expression of the katG gene, contributing to increased bacterial antioxidant defenses (Di Martino et al, 2013).…”

Comparative Review of the Responses of Listeria monocytogenes and Escherichia coli to Low pH Stress

“…High-resolution X-ray crystal structures of GadC [123] and AdiC [117,124,125] have been solved and a model for substrate binding and conformational changes associated with the AdiC transport cycle has been proposed. Current knowledge on the structures, transport mechanisms, and regulation of these acid resistance associated antiporters have been recently reviewed [126]. Interestingly, the antiporters of each decarboxylation system in E. coli possess an invariant glutamic acid in the intermembrane domain that has been proposed to act as a pH sensor [117].…”