PrbP modulates biofilm formation in Liberibacter crescens

Abstract

Summary In Liberibacter asiaticus, PrbP is a transcriptional regulatory protein involved in survival and persistence during host infection. Tolfenamic acid was previously found to inhibit interactions between PrbP and the promotor region of rplK, resulting in reduced survival of L. asiaticus in the citrus host. In this study, we performed transcriptome analyses to elucidate the PrbP regulon in L. crescens, as it is phylogenetically the closest related species to L. asiaticus that can be grown in laboratory conditions. Chemical inhibition of PrbP with tolfenamic acid revealed that PrbP is involved in the regulation of diverse cellular processes, including stress response, cell motility, cell cycle and biofilm formation. In vitro DNA binding and bacterial two‐hybrid assays also suggested that PrbP is a global regulator of multiple transcription factors (RpoH, VisN, PleD, MucR, MocR and CtrA) at both transcriptional and/or post‐transcriptional levels. Sub‐lethal concentrations of tolfenamic acid significantly reduced the attachment of L. crescens during biofilm formation and decreased long‐term persistence in biofilm structures. Overall, our findings show the importance of PrbP in regulating diverse biological processes through direct and indirect interactions with other transcriptional regulators in L. crescens.

Osmotic stress induces long-term biofilm survival in Liberibacter crescens

“…2 A, Table S7 ). The range of fold change obtained is in line with our previous reports involving chemical inactivation of transcriptional regulators in L. crescens [ 20 , 32 ]. As previously suggested, a contributing factor to these small changes in gene expression may be the high duplication time of L. crescens, which further leads to low transcriptional activity.…”

“…asiaticus [ 51 ], and their involvement was proposed in the initial attachment and colonization of the bacterium within the host. In agreement with these observations, we recently reported that in L. crescens , the global regulator PrbP binds to the promoter region of visN and up-regulates its expression under biofilm forming conditions [ 32 ]. PrbP was also found to induce the expression of mucR , consequently repressing the expression of rem , an activator of motility genes [ 32 ].…”

“…In agreement with these observations, we recently reported that in L. crescens , the global regulator PrbP binds to the promoter region of visN and up-regulates its expression under biofilm forming conditions [ 32 ]. PrbP was also found to induce the expression of mucR , consequently repressing the expression of rem , an activator of motility genes [ 32 ]. While VisN has been reported to form a heterodimer with VisR to regulate gene expression in other bacterial systems [ 51 , 52 ], recent evidence suggests that in L .…”

“…While the category transcription (K) did not have statistical significance ( p = 0.169), several transcriptional and translational regulators, including fur/zur , visN , dksA , and pleD, were significantly up-regulated (1.27, 1.27, 1.25, and 1.33-fold, respectively, p adj < 0.05) (Table S3 ). Interestingly, some of these proteins have been reported to regulate some processes of the enriched COG categories, and were also found to control the expression of stress responses, cell cycle, and biogenesis of extracellular elements [ 32 ]. While L .…”

“…The pellet was washed once by suspending in 3 ml of bBM7 (BM7 media without FBS) and collected by centrifugation as described above. The pellet was subsequently re-suspended at OD 600 = 0.1 in BM7 or bBM7, supplemented with 0.75 mg/ml of methyl-β-cyclodextrin [ 32 ]. Where indicated, BM7 and bBM7 media was supplemented with sucrose (100 mM) or DMSO (0.05%).…”