Identification and molecular analysis of superoxide dismutase isoforms in Helicobacter pylori

Three electromorphs of iron superoxide dismutase (FeSOD) were identified am ong 29 Helicobacter pylori isolates by native gel electrophoresis and activ ity staining. The electromorphs designated isoforms A, B, and C are charact erized by slow, intermediate and fast electrophoretic migration, respective ly, which was not observed under denaturing conditions. The isoforms were n ot associated with virulence determinants and with the outcome of disease. Sequence analysis of the sodB gene in strains producing different FeSOD iso forms and comparison of deduced protein sequences revealed that differences in the electric migration behavior are associated with exchange of charged amino acids, suggesting that faster migration is caused by a more negative total charge of the proteins. Electrophoretic migration of native FeSOD wa s not influenced by changes in the iron cofactor concentration, oxidative s tress, and different media, indicating that FeSOD isoforms represent stable strain-specific markers. (C) 2000 Federation of European Microbiological S ocieties. Published by Elsevier Science B.V. All rights reserved.