Localisation of Helicobacter pylori catalase in both the periplasm and cytoplasm, and its dependence on the twin-arginine target protein, KapA, for activity

• Published in: FEMS microbiology letters 2003-12, Vol.229 (2), p.283-289
• Main Authors: Harris, Andrew G., Hazell, Stuart L.
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Arginine - metabolism; Bacterial Proteins - chemistry; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Bacteriology; Base Sequence; Biological and medical sciences; Catalase - chemistry; Catalase - genetics; Catalase - metabolism; Catalase-associated protein; Cytoplasm - enzymology; Fundamental and applied biological sciences. Psychology; Helicobacter pylori; Helicobacter pylori - enzymology; Helicobacter pylori - genetics; Microbiology; Miscellaneous; Molecular Sequence Data; Mutagenesis, Site-Directed; Oxidative Stress; Periplasm - enzymology; Periplasmic localization; Protein Structure, Secondary; Site-directed mutagenesis
• ISSN: 0378-1097; 1574-6968
• DOI: 10.1016/S0378-1097(03)00850-4

Helicobacter pylori induces a severe inflammatory response in the gastric mucosa. It is able to withstand the inflammatory response by producing proteins such as KatA and KapA. The C-terminus of KatA possesses a unique tetra-lysine motif not found in other catalases or other known protein sequences. Mutants deficient in this motif were constructed by site-directed mutagenesis. Cytoplasmic and periplasmic catalase activities were measured for the parental strain, a truncated KatA mutant (deficient in the unique C-terminal tetra-lysine motif) and a previously constructed KapA-deficient mutant (confirming previous observations regarding the possible periplasmic localisation of KatA). No differences were observed in the cytoplasmic catalase activities, however, the KapA-deficient mutant had approximately 5.5 times less catalase activity in the periplasmic extract when compared to the periplasmic preparations of either parental strain or KatA truncated mutant. N-terminal sequencing of KatA revealed no cleaved N-terminal signal peptide, indicating Sec-independent transport. These findings support previous reports that there is some form of interaction between KatA and KapA of H. pylori, an interaction which still needs to be characterised.