Participation of two general stress response proteins from Xanthomonas citri subsp. citri in environmental stress adaptation and virulence

BARCAROLO, MARÍA VICTORIA; GOTTIG, NATALIA; OTTADO, JORGELINA; GARAVAGLIA, BETIANA S

FEMS MICROBIOLOGY ECOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Año: 2020 vol. 96

0168-6496

Xanthomonas citri subsp. citri (Xcc) is the bacteria responsible for citrus canker. During its life cycle Xcc is found on leaves asepiphyte, where desiccation conditions may occur. In this work, two Xcc genes, XAC0100 and XAC4007, predicted in silico tobe involved in general stress response, were studied under salt, osmotic, desiccation, oxidative and freezing stress, andduring plant-pathogen interaction. Expression of XAC0100 and XAC4007 genes was induced under these stress conditions.Disruption of both genes in Xcc caused decreased bacterial culturability under desiccation, freezing, osmotic and oxidativestress. Importantly, the lack of these genes impaired Xcc epiphytic fitness. Both Xac0100 and Xac4007 recombinant proteinsshowed protective effects on Xanthomonas cells subjected to drought stress. Also, Escherichia coli overexpressing Xac4007showed a better performance under standard culture, saline and osmotic stress and were more tolerant to freezing andoxidative stress than wild type E. coli. Moreover, both Xac0100 and Xac4007 recombinant proteins were able to prevent thefreeze-thaw-induced inactivation of L-Lactate dehydrogenase. In conclusion, Xac0100 and Xac4007 have a relevant role asbacteria and protein protectors; and these proteins are crucial to bacterial pathogens that must face environmentalstressful conditions that compromise the accomplishment of the complete virulence process.