PMID:8955320

Citation	Odenbreit, S, Wieland, B and Haas, R (1996) Cloning and genetic characterization of Helicobacter pylori catalase and construction of a catalase-deficient mutant strain. J. Bacteriol. 178:6960-7
Abstract	The N-terminal sequence of a protein, originally described as an adhesin of Helicobacter pylori, was used in an oligonucleotide-based screening procedure of an H. pylori plasmid library in Escherichia coli. Five independent plasmid clones were isolated, all mapping to the same chromosomal region and encoding the H. pylori catalase. The gene, designated katA, comprises 1,518 nucleotides and encodes a putative protein of 505 amino acids with a predicted Mr of 58,599. A second open reading frame, orf2, encoding a putative 32,715-Da protein of unknown function, follows katA. The transcriptional start site of katA mRNA was determined, but no typical consensus promoter sequence was present. A potential binding site for the Fur protein is located upstream of katA. When introduced into the catalase-deficient E. coli double-mutant UM255, the cloned gene readily complemented E. coli for catalase activity. H. pylori KatA is highly homologous to catalases in both prokaryotes and eukaryotes, with the highest homology being shown to Bordetella pertussis (64.9%), Bacteroides fragilis (59.8%), and Haemophilus influenzae (57.9%) catalases. Transposon insertion mutants were generated in three independent H. pylori strains by TnMax5-mediated transposon shuttle mutagenesis. In contrast to the wild-type strains, no significant catalase-specific enzymatic activity could be detected in the mutant strains, consistent with the fact that no additional katA-homologous gene copies were found in the H. pylori chromosome. No significant difference between wild-type and mutant strains for binding to epithelial cells was apparent, suggesting that KatA is not involved in H. pylori adhesion. The cloning and genetic characterization of katA are essential steps for further investigation of the role of catalase in the defense of H. pylori against oxygen-dependent killing mechanisms by polymorphonuclear granulocytes, a process not well understood for this chronically persisting pathogen.
Links	PubMed PMC178599
Keywords	Amino Acid Sequence; Bacteriophage T7/genetics; Base Sequence; Catalase/chemistry; Catalase/genetics; Catalase/metabolism; Cloning, Molecular; DNA Transposable Elements; Escherichia coli/genetics; Gene Expression; Gene Expression Regulation, Bacterial; Genes, Bacterial; Helicobacter pylori/enzymology; Helicobacter pylori/genetics; Molecular Sequence Data; Molecular Weight; Mutagenesis, Insertional; Open Reading Frames/genetics; Plasmids; Promoter Regions, Genetic; Sequence Analysis, DNA
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
HELPY:CATA		GO:0042744: hydrogen peroxide catabolic process	ECO:0000315:		P		Under Results, section "Construction and characterization of catalase-deficient H. pylori mutant strains by transposon shuttle mutagenesis": The insertional inactivation of the chromosomal katA gene completely abolished catalase activity, which was measured by the disappearance of hydrogen peroxide. The wild-type strain (which contained katA but lacked known catalases) produced a high level of specific catalase activity (4,422 U/mg), but the katA mutant revealed only background activity (5 U/mg).	complete CACAO 6212
HELPY:CATA	involved_in	GO:0042744: hydrogen peroxide catabolic process	ECO:0000315: mutant phenotype evidence used in manual assertion		P		Seeded From UniProt	complete

References

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