Consistent with this, a recent work showed that a X. citri
mutant in XAC0019 displays reduced capacity to form SN-38 chemical structure a biofilm  and its expression is increased during X. citri biofilm formation . In the present study, XAC0019 protein was down-regulated in the hrpB − mutant impaired in biofilm formation, reinforcing the role of this protein in this process. Enzymes involved in EPS production XanA and GalU, [30, 31] were up-regulated in the hrpB − mutant. Consistently, all the hrp mutant analyzed in this work produced larger amounts of EPS in comparison with X. citri and also had higher expression levels of gumD. Recent MK-4827 chemical structure reports have shown that X. citri galU mutant strain is not pathogenic and also
loses its capacity to form a biofilm due to a reduction in EPS production [30, 32], and that a X. citri xanA mutant has an altered capacity for biofilm formation LDN-193189 research buy . Although, the hrp mutants are impaired in biofilm formation, these mutants produce more EPS than X. citri. This interesting result open new hypotheses about the link between T3SS and EPS production, thus further studies are needed to unravel this issue. In other pathogens, such as P. aeruginosa, T3SS gene expression is coordinated with many other cellular activities including motility, mucoidy, polysaccharide production, and also biofilm formation . Bacterial motility was impaired in the hrp mutants and consistently,
proteins known as involved in these processes such as the outer membrane protein XAC0019  and the bactofilin CcmA [33, 34] were down-regulated in the hrpB − mutant. Besides, swarming motility was less affected than swimming in the hrp mutants selleck chemical compared with X. citri. This may be due to the fact that in X. citri swarming motility depends on flagella and also on the amount of EPS secreted , and since these mutants over-produced EPS swarming was less affected than swimming. This work demonstrated that in X. citri T3SS is involved in multicellular processes such as motility and biofilm formation. Furthermore, our results suggest that T3SS may also have an important role in modulating adaptive changes in the cell, and this is supported by the altered protein expression when this secretion system is not present. It was previously shown that an E. coli O157 strain mutant in the additional T3SS named ETT2 is impaired in biofilm formation . It was also suggested that deletion of ETT2 might cause structural alterations of the membrane modifying bacterial surface properties, thus affecting bacteria-bacteria interactions or the interaction with host cells . Further, it was proposed that these structural alterations could trigger a signal that activates differential gene expression and/or protein secretion .