Properties of the HtrA Protease From Bacterium Helicobacter pylori Whose Activity Is Indispensable for Growth Under Stress Conditions

• Published in: Frontiers in microbiology 2019-05, Vol.10, p.961-961
• Main Authors: Zarzecka, Urszula, Modrak-Wójcik, Anna, Figaj, Donata, Apanowicz, Malgorzata, Lesner, Adam, Bzowska, Agnieszka, Lipinska, Barbara, Zawilak-Pawlik, Anna, Backert, Steffen, Skorko-Glonek, Joanna
• Format: Article
• Language: English
• Subjects: Helicobacter pylori; HtrA; Microbiology; protein quality control system; proteolytic activity; stress endurance; virulent factor
• ISSN: 1664-302X; 1664-302X
• DOI: 10.3389/fmicb.2019.00961

The protease high temperature requirement A from the gastric pathogen (HtrA ) belongs to the well conserved family of serine proteases. HtrA is an important secreted virulence factor involved in the disruption of tight and adherens junctions during infection. Very little is known about the function of HtrA in the cell physiology due to the lack of knockout strains. Here, using a newly constructed Δ mutant strain, we found that bacteria deprived of HtrA showed increased sensitivity to certain types of stress, including elevated temperature, pH and osmotic shock, as well as treatment with puromycin. These data indicate that HtrA plays a protective role in the cell, presumably associated with maintenance of important periplasmic and outer membrane proteins. Purified HtrA was shown to be very tolerant to a wide range of temperature and pH values. Remarkably, the protein exhibited a very high thermal stability with the melting point (T ) values of above 85°C. Moreover, HtrA showed the capability to regain its active structure following treatment under denaturing conditions. Taken together, our work demonstrates that HtrA is well adapted to operate under harsh conditions as an exported virulence factor, but also inside the bacterial cell as an important component of the protein quality control system in the stressed cellular envelope.