Characterization and pathogenicity of extracellular serine protease MAP3292c from Mycobacterium avium subsp. paratuberculosis

Hongxiu Liu; Guanghui Dang; Xinxin Zang; Zhuming Cai; Ziyin Cui; Ningning Song; Siguo Liu

doi:10.1016/j.micpath.2020.104055

Characterization and pathogenicity of extracellular serine protease MAP3292c from Mycobacterium avium subsp. paratuberculosis

Microb Pathog. 2020 Feb 11:142:104055. doi: 10.1016/j.micpath.2020.104055. Online ahead of print.

Authors

Hongxiu Liu¹, Guanghui Dang¹, Xinxin Zang¹, Zhuming Cai¹, Ziyin Cui¹, Ningning Song¹, Siguo Liu²

Affiliations

¹ State Key Laboratory of Veterinary Biotechnology, Division of Bacterial Diseases, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, 678 Haping Street, Harbin, 150069, PR China.
² State Key Laboratory of Veterinary Biotechnology, Division of Bacterial Diseases, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, 678 Haping Street, Harbin, 150069, PR China. Electronic address: liusiguo@caas.cn.

PMID: 32058021
DOI: 10.1016/j.micpath.2020.104055

Abstract

Serine protease is the virulence factor of many pathogens. However, there are no prevailing data available for serine protease as a virulence factor derived from Mycobacterium avium subsp. paratuberculosis (MAP). The MAP3292c gene from MAP, the predicted serine protease, was expressed in Escherichia coli and characterized by biochemical methods. MAP3292c protein efficiently hydrolyzed casein at optimal temperature and pH of 41 °C and 9.0, respectively. Furthermore, divalent metal ions of Ca²⁺ significantly promoted the protease activity of MAP3292c, and MAP3292c had autocleavage activity between serine 86 and asparagine 87. Site-directed mutagenesis studies showed that the serine 238 residue had catalytic roles in MAP3292c. Furthermore, a BALB/c mouse model confirmed that MAP3292c significantly promoted the survival of Mycobacterium smegmatis in vivo; caused damage to the liver, spleen, and lung; and promoted the release of inflammatory cytokines IL-1β, IL-6, and TNF-α in mice. Finally, we confirmed that MAP3292c was relevant to mycobacterial pathogenicity.

Keywords: MAP3292c; Mycobacterium avium subsp. paratuberculosis; Mycobacterium smegmatis; Pathogenicity; Serine protease.