Expression, purification, and analysis of toxins from toxin-antitoxin system (TA) of Xylella fastidiosa

Abstract

Biofilm formation is considered Xylella fastidiosa's main mechanism of pathogenicity. Cells in the biofilm have adaptive advantages such as increased resistance to a broad range of microbial agents which difficult to the control the bacterial population. Another mechanism associated with tolerance to antimicrobial compounds is the formation of persistent cells, which do not multiply nor die in the presence of bactericidal agents. It was found by our group that induction of persister X.fastidiosa cells is related to the expression of type II toxin-antitoxin system (TA), in which both toxin and antitoxin are proteins. Several TA system genes of the X.fastidiosa genome were found, and many of them are annotated as hypothetical. Studies by the group show that these genes have a direct implication on the host plant. Even after the action of high doses of antimicrobial compounds persistent cells could still recover and recolonize the environment. This may represent an important strategy for the survival of the population. The purpose of this research is to verify the toxic effect of some TA system toxins from X.fastidiosa in contact with other bacteria. It is speculated that they are secreted by the cell due to the fact of presenting a reduced size. The possible toxic effects of some toxins in the growth of Xylella fastidiosa, Xanthomonas citri and Curtobacterium flaccumfaciens will be determined. (AU)