Heme binding and peroxidase activity of a secreted minicatalase

作者：Mori Giulia^*; Doniselli Nicola; Faroldi Federica; Percudani Riccardo^*

来源：FEBS LETTERS, 2016, 590(24): 4495-4506.

DOI：10.1002/1873-3468.12493

• disulfide bond
• heme binding
• host-pathogen interaction
• hydrogen peroxide
• oxidative stress
• periplasmic protein

Microbial pathogens often require efficient and robust H2O2 scavenger activities to survive in the presence of reactive oxygen species generated by inflammatory responses. In addition to catalases and peroxidases, enzymes known to scavenge H2O2, a novel class of secreted minicatalases is found in diderm bacteria. Here, we characterize the Helicobacter pylori (Hp) minicatalase: a monomeric hemoprotein with catalase core homology. Overexpression of Hp minicatalase rescued a catalase/peroxidase-deficient Escherichia coli phenotype under aerobic conditions and limited H2O2 stress. The purified enzyme lacks catalase activity, but has strong (k(cat) > 100 s(-1)) H2O2-dependent peroxidase activity toward a variety of organic substrates. Our investigations into heme binding revealed that the heme cofactor is assembled in the periplasm to form the functional holoprotein. Furthermore, we observed the presence of a disulfide bond near the heme cavity of Hp minicatalase, which is conserved in secreted minicatalases and, therefore, may play a role in heme binding.

• 出版日期2016-12