Functional analysis of the CRP and TreR-treBC regulon in trehalose utilization of Vibrio parahaemolyticus

Abstract

Vibrio parahaemolyticus is an important foodborne pathogen recognized for its adaptability to various environmental conditions. Understanding its metabolic pathways is crucial for elucidating its survival and pathogenicity. This study investigates the metabolism of trehalose as a carbon source in V. parahaemolyticus and explores its effects on bacterial growth and virulence. We found that V. parahaemolyticus can utilize trehalose as a sole carbon source for growth and identified the presence of treBC operon, which is crucial for trehalose degradation. Notably, the ΔtreB and ΔtreC strains exhibited impaired growth when trehalose was used as the sole carbon source in both high and low osmolarity, indicating the essential role of treBC operon in trehalose metabolism. Moreover, our results revealed that the repressor TreR inhibits treBC expression by directly binding to its promoter, with two specific binding sites (T1 and T2). When presence of trehalose, the metabolites trehalose-6-phosphate inhibited the binding of TreR to treBC promoter. Furthermore, we found that the cAMP-CRP complex can directly bind to the promoter of treBC and promote its expression. The competitive EMSA results indicated that TreR has a competitive binding advantage over CRP, allowing it to preferentially bind to the treBC promoter and thereby prevent CRP binding. Together, our findings highlight the complex regulatory mechanisms governing trehalose metabolism in V. parahaemolyticus.