The phosphoenolpyruvate (PEP): carbohydrate phosphotransferase system (PTS) allows bacteria to use various carbohydrates as energy resources including mannitol. The mannitol-specific PTS transporter in Vibrio cholerae is encoded by the mtlADR operon. Expression of the mtl operon has been shown to be strictly regulated by CRP, MtlS, and MtlR. In the present study, we investigated the regulation of mtlADR by the ferric uptake regulator (Fur). The results showed that Fur binds to the promoter-proximal DNA region of mtlADR to repress its transcription independent of iron, in mannitol-containing growth medium. The capacity for mannitol fermentation was significantly increased in Δfur relative to that of WT for normal and iron-replete growth media. The level of organic acids produced by Δfur was significantly enhanced relative to that produced by the WT strain in the normal and iron-replete media but not in an iron-starved medium. The results provided for a deeper understanding of the regulation of mtlADR in V. cholerae.

磷酸烯醇丙酮酸 (PEP)：碳水化合物磷酸转移酶系统 (PTS) 允许细菌使用各种碳水化合物作为能源，包括甘露醇。霍乱弧菌中甘露醇特异性 PTS 转运蛋白由mtlADR操纵子编码。mtl操纵子的表达已被证明受到 CRP、MtlS 和 MtlR 的严格调控。在本研究中，我们研究了三价铁摄取调节剂 (Fur)对mtlADR的调节。结果表明，在含甘露醇的生长培养基中，Fur 与mtlADR的启动子近端 DNA 区域结合以抑制其转录，而无需铁。Δ fur中甘露醇发酵能力显着增加相对于正常和富含铁的生长培养基的 WT。Δ fur产生的有机酸水平相对于正常和富铁培养基中的 WT 菌株产生的水平显着提高，但在缺铁培养基中则不然。提供的调控有了更深的了解，结果mtlADR在霍乱弧菌。