In several bacterial pathogens—including Escherichia coli (E. coli), Yersinia enterocolitica, Helicobacter pylori (H. pylori), Listeria monocytogenes, and S. pneumoniae—HtrA plays an important role in infection by proteolyzing misfolded proteins (Backert et al., 2018; de Stoppelaar et al., 2013; Heusipp et al., 2004; Radhakrishnan et al., 2021; Zhang et al., 2019). The gene discussed is HTRA1; the disease is infection.