Characterization of the Arginine Decarboxylase Gene (ORF HP0422, speA) Involved in Acid Tolerance in Helicobacter pylori

Abstract

Altogether, these results provide novel information regarding the H. pylori physiology and acid response mechanism.

The DNA‐Binding Protein HU has a Regulatory Role in the Acid Stress Response Mechanism in Helicobacter pylori

“…Among those proteins, we have identified the urease subunits UreA and UreB, Pfr, NapA, and the DNA-binding protein HU [9,10]. We have also shown that the Fur-regulated (ferric uptake regulator) arginine decarboxylase gene, speA, is overexpressed under acid stress conditions [11,12]. The speA gene is homologue to adiA from Escherichia coli, a gene that participates in the acid response system 3 (AR3).…”

Biochemical and biophysical studies of Helicobacter pylori arginine decarboxylase, an enzyme important for acid adaptation in host

“…The HP0422 gene of H. pylori 26695 strain has been shown to encode for arginine decarboxylase . In general, biosynthetic arginine decarboxylases require PLP and the divalent Mg 2+ ion as cofactors for decarboxylation reaction.…”

“…In the absence of an annotated L‐ornithine decarboxylase gene in H. pylori 26695 strain, the pathway in which the metabolism of L‐arginine by ADC occurs, may be crucial for the synthesis of polyamines. This enzyme has also been suggested to be important for acid adaptation of the bacterium in the host . However, it has not been studied at a molecular level.…”

“…Like other arginine decarboxylases (ADCs), the H. pylori enzyme has been shown to catalyze the conversion of L‐arginine to agmatine and CO 2 . However, the survival of urease negative strain of H. pylori suggests the involvement of an unknown mechanism in the acid adaptation . Enteropathogenic bacteria such as E. coli ( Escherichia coli ), S. enterica ( Salmonella enterica ), and Y. pestis ( Yersinia pestis ) have developed sophisticated acid resistance system (AR3) to survive in the extremely acidic environment of the stomach.…”

“…To neutralize the pH of the stomach, it transports L‐arginine (+1 charge) into and agmatine (+2 charge) out of the cell, which result in the export of 1 proton during each turnover and thus the bacteria can survive in the acidic environment . It is suggested that the ADC gene of H. pylori could be involved in an acid adaptation mechanism similar to the one in E. coli . This indicates that the metabolism of L‐arginine by ADC in H. pylori might be crucial for its survival in the acidic environment.…”