Fumarate reductase of Helicobacter pylori--an immunogenic protein

Abstract

Summary. An immunogenic protein with an apparent mol. wt of 80 kDa that was recognised by 55 % of sera from patients infected with Helicobacter pylori in Western blots was found in butanol extracts of H. pylori membranes. The N-terminal amino-acid sequence of the 80-kDa protein showed 80% identity with the N-terminal sequence of subunit A of the fumarate reductase of Wolinella succinogenes, suggesting the existence of a fumarate reductase in H. pylori. The membrane fraction of H. pylori catalysed succinate oxidation with methylene blue at a specific enzyme activity of 0.06 U/mg of protein. The enzyme was purified by Triton X 100 extraction followed by ion-exchange chromatography. The purified enzyme contained an 80-kDa protein which was recognised by rabbit serum raised against subunit A of fumarate reductase of W . succinogenes. A second protein band with a mol. wt of 3 1 kDa was recognised by rabbit serum raised against subunit B of fumarate reductase of W . succinogenes. Two-dimensional gel electrophoresis demonstrated that the 80-and 3 1 -kDa proteins were subunits of one protein complex. These results indicate that H . pylori contains an enzyme that is very similar to W. succinoyenes fumarate reductase. The 80-kDa subunit was recognised in sonicates of all 32 H. pylori strains tested by rabbit antibodies raised against subunit A of fumarate reductase of W. succinogenes, indicating that fumarate reductase is a common protein in H. pylori. The fumarate reductase of H . pylori might enable the bacterium to perform anaerobic respiration in a similar fashion to other anaerobic or facultative bacteria.

Complexomics Study of Two Helicobacter pylori Strains of Two Pathological Origins

“…It was also noted that the M r of FrdB was higher than that of FrdC, whereas their deduced M r values were in the same range. This apparent migration of FrdB at 31 kDa was reported previously by Birkholz et al (35). The FRD complex, commonly associated with the membrane of H. pylori (37), is the key enzyme of the Krebs cycle involved in fumarate respiration in the case of anaerobic growth.…”

“…1, A and B, and 2, A-C, E, and J), but a spot corresponding to FrdA presented a slightly oval shape, whereas spots corresponding to FrdB/C had a rounded and more diffuse shape due to a more diffuse gel migration in the lower approximate M r range (28). However, these three proteins correspond to the three subunits of the fumarate reductase (FRD) complex of H. pylori (35,36), and FrdA and FrdB were found previously in a membrane complex of the J99 strain using the twodimensional BN/SDS-PAGE method (28). Consequently, this complex was included given that its third evident partner, FrdC, was identified on most of the gels (Figs.…”

Two-dimensional Blue Native/SDS Gel Electrophoresis of Multiprotein Complexes from Helicobacter pylori

“…The co-migration in the first dimension seems to be correct because these two spots were observed several times (data not shown). Moreover, these proteins (spots 42 and 43) have been identified previously as the subunits A and B of the fumarate reductase (FrdA and FrdB) of H. pylori (48). This complex was named M2.…”

Potential of fumarate reductase as a novel therapeutic target in Helicobacter pylori infection

“…This was demonstrated by 1D and 2D 1 H-13 C NMR spectroscopy showing that the conversion of fumarate to succinate via FRD and malate by fumarase occurs at a high rate in vitro [43]. In addition, strong FRD activity can be detected in H. pylori cultures [31,44,45]. These results suggest that FRD in H. pylori is constitutively expressed, which is consistent with the fact that the FNR-binding sequence in the promoter region of the E. coli frd operon is absent in H. pylori (Figure 1) [46].…”