GENERAL STRESS RESPONSE PROTEINS FROM XANTHOMONAS CITRI SUBSP. CITRI INVOLVED IN STRESS ADAPTATION AND VIRULENCE

GOTTIG, N.; BARCAROLO, M.V.; GARAVAGLIA, B.S.; JORGELINA OTTADO

Rosario

Congreso; Congreso Conjunto SAIB-SAMIGE 2020; 2020

Asociación Argentina de Microbiología- Sociedad Argentina de Investigación Bioquímica y Biología Molecular

Xanthomonas citri subsp. citri (Xcc) causes citrus canker that can result in defoliation and premature fruit drop with significant production losses worldwide. During its life cycle Xcc is found on leaves as epiphyte, where desiccation conditions take place. In this work, two Xcc genes, XAC0100 and XAC4007, predicted by bioinformatic analysis to be involved in general stress response, were studied under salt, osmotic, desiccation, oxidative and freezing stress, and during plant-pathogen interaction. Expression of XAC0100 and XAC4007 genes was induced under these stress conditions. Disruption of both genes in Xcc caused diminished bacteria culturability under desiccation, freezing, osmotic and oxidative stress. Moreover, the lack of these genes significantly impaired Xcc epiphytic fitness. Besides, both Xac0100 and Xac4007 recombinant proteins showed protective effects on Xanthomonas cells subjected to drought stress. Also, Escherichia coli overexpressing Xac4007 showed a better performance under standard culture, saline and osmotic stress and were more tolerant to freezing and oxidative stress than wild type E. coli. Both Xac0100 and Xac4007 recombinant proteins were able to avoid the freeze-thaw-induced inactivation of L-Lactate dehydrogenase enzyme. In conclusion, Xac0100 and Xac4007 have a relevant role as bacteria and protein protectors; and these proteins are crucial to bacterial pathogens that must face environmental stressful conditions that compromise the virulence process.