The multifunctional role of the protease <scp>HtrA</scp> in <i>Helicobacter pylori</i> pathogenesis

The HtrA family of proteins is known for its dual role as chaperones and proteases. In Helicobacter pylori (H. pylori), HtrA's chaperone and proteolytic activities are crucial for the bacterium's survival and successful host infection. Compared to other HtrA homologs in Gram-negative bacteria, HtrA of H. pylori (HtrA_Hp) is rather well-understood. HtrA is localized in two cellular compartments, performing critical functions within the bacterial periplasm as well as in the extracellular milieu. This review aimed to summarize the current knowledge on HtrA_Hp and provide comprehensive information about (i) the structure, oligomerization, and general properties of HtrA_Hp, (ii) its chaperone and proteolytic activity in the stress response and the protein quality control system in the periplasm, and (iii) the functional role of HtrA_Hp in opening lateral cell junction complexes of epithelial cells as an important step in infectivity. Due to its essential physiological role and its contribution to the pathologic consequences of infection, HtrA represents a highly attractive target for novel therapeutic strategies.