Characterization of Helicobacter pylori adhesin thiol peroxidase (HP0390) purified from Escherichia coli

Abstract

The antioxidant protein, adhesin thiol peroxidase (HpTpx or HP0390), plays an important role in enabling Helicobacter pylori to survive gastric oxidative stress. The bacterium colonizes the host stomach and produces gastric cancer. However, little information is available about the biochemical characteristics of HpTpx. We expressed recombinant HpTpx in Escherichia coli, purified to homogeneity, and characterized it. The results showed that HpTpx existed in a monomeric hydrodynamic form and the enzyme fully retained its peroxidase and antioxidant activities. The catalytic reaction of the enzyme was similar to an atypical 2-cysteine peroxiredoxin (Prx). The conformation of the enzyme was observed in the presence and absence of dithiothreitol (DTT); similar to other known thiol peroxidases, conformational change was observed in HpTpx by the addition of DTT.

The histone‐like protein HU has a role in gene expression during the acid adaptation response in Helicobacter pylori

“…Mutant strains for that protein have less adherence ability to gastric epithelium. 52 HypB is a metallo-chaperone that is involved in [Ni-Fe]-hydrogenase synthesis. 53 AhpC is a peroxiredoxine playing an important role during the oxidative stress and in host colonization.…”

“…Our present results show that at neutral pH, GroES, and CheZ are less expressed in the H. pylori hup::cat mutant compared with the wild-type strain. Mutant strains for that protein have less adherence ability to gastric epithelium 52. CheA is the sensor of the two-component system CheA-CheY, which regulates the movement of flagella by adjusting it to chemical changes in the environment, 47,48 such as the higher H + ion concentration associated with acid stress.…”

Helicobacter pyloridefense against oxidative attack

“…AhpC from H. pylori and other bacterial species also possess activity against peroxynitrite, which has not been observed for the other enzymes (15). The enzymes are distinguished by the number of conserved cysteine residues within the structure, with AhpC classified as a "typical" 2-Cys Prx (78), Hp-Tpx as an "atypical" 2-Cys Prx (70), and Bcp as a 1-Cys Prx (103). Typical and atypical 2-Cys Prxs differ in the conformation of the disulfide bond that forms upon oxidation of the cysteine residues: the disulfide bond of typical 2-Cys Prx is intermolecular, leading to dimer formation, whereas the bond in atypical 2-Cys Prx is intramolecular, resulting in monomer formation (83).…”

“…However, it has recently been suggested that atypical 2-Cys Prxs may also exist in multimeric forms (10,84). Ngyuen et al (70) found Hp-Tpx to be a purely monomeric, 18-kDa protein. However, nuclear magnetic resonance analysis of the enzyme detected peaks of higher molecular weight (70) that may represent multimeric forms.…”

Oxidative and nitrosative stress defences ofHelicobacterandCampylobacterspecies that counteract mammalian immunity

“…Tpx and BCP belong to the 2-Cys peroxiredoxin family and are involved in oxidative stress defence in Helicobacter and Campylobacter species (Nguyen et al 2010).…”