乙酸细菌用于许多工业过程,例如醋的生产,维生素C,抗糖尿病药物米格列醇,和各种人造调味品。这些在工业上重要的反应主要由面向周质的膜结合的脱氢酶库进行,这些脱氢酶不完全氧化其底物并将电子直接穿梭到呼吸链中。在这些脱氢酶中,氧化葡糖杆菌中的GOX1969被预测为功能未知的吡咯并喹啉醌依赖性脱氢酶。然而,经过多个实验室的多重分析,未检测到脱氢酶活性。对GOX1969序列和结构的重新分析揭示了与大肠杆菌BamB的相似性,其作为β-桶组装机械复合物的亚基起作用,该复合物负责革兰氏阴性细菌中β-桶外膜蛋白的组装。为了测试GOX1969的生理功能是否与大肠杆菌中的BamB相似,我们将gox1969基因引入大肠杆菌ΔbamB突变体中。当gox1969在质粒pGox1969上表达时,ΔbamB突变体的生长缺陷得以恢复。此外,gox1969表达后,bamB缺失赋予的膜通透性增加恢复,这表明GOX1969与维持外膜稳定性的作用之间存在直接联系。一起,这一证据强烈表明,GOX1969在G.oxydans中在功能上充当BamB。因此,关于未表征基因的功能信息将提供新的见解,这些见解将允许对乙酸细菌代谢进行更准确的建模,并进一步努力设计用于工业用途的合理菌株。氧化葡糖杆菌是乙酸细菌的工业重要成员。推定基因的实验表征对于确定可用于维生素C生产的合理乙酸菌株的进一步工程的目标是必要的,抗糖尿病化合物,人造调味品,或新型化合物。在这项研究中,我们已经鉴定了一种未定义的脱氢酶GOX1969,没有已知的底物,并且与大肠杆菌K12中的外膜生物发生蛋白BamB具有明确的结构相似性。此外,我们证明GOX1969能够补充大肠杆菌K12中的bamB敲除表型。一起来看,这些发现增强了我们对氧化黑曲霉生理学的理解,并扩展了未来工业菌株设计的潜在目标列表.
Acetic acid bacteria are used in many industrial processes such as the production of vinegar, vitamin C, the antidiabetic drug miglitol, and various artificial flavorings. These industrially important reactions are primarily carried out by an arsenal of periplasmic-facing membrane-bound dehydrogenases that incompletely oxidize their substrates and shuttle electrons directly into the respiratory chain. Among these dehydrogenases, GOX1969 in Gluconobacter oxydans was predicted to be a pyrroloquinoline quinone-dependent dehydrogenase of unknown function. However, after multiple analysis by a number of labs, no dehydrogenase activity has been detected. Reanalysis of GOX1969 sequence and structure reveals similarities to Escherichia coli BamB, which functions as a subunit of the β-barrel assembly machinery complex that is responsible for the assembly of β-barrel outer membrane proteins in Gram-negative bacteria. To test if the physiological function of GOX1969 is similar to BamB in E. coli, we introduced the gox1969 gene into an E. coli ∆bamB mutant. Growth deficiencies in the ∆bamB mutant were restored when gox1969 was expressed on the plasmid pGox1969. Furthermore, increased membrane permeability conferred by bamB deletion was restored upon gox1969 expression, which suggests a direct link between GOX1969 and a role in maintaining outer membrane stability. Together, this evidence strongly suggests that GOX1969 is functionally acting as a BamB in G. oxydans. As such, functional information on uncharacterized genes will provide new insights that will allow for more accurate modeling of acetic acid bacterial metabolism and further efforts to design rational strains for industrial use.IMPORTANCEGluconobacter oxydans is an industrially important member of the acetic acid bacteria. Experimental characterization of putative genes is necessary to identify targets for further engineering of rational acetic acid bacteria strains that can be used in the production of vitamin C, antidiabetic compounds, artificial flavorings, or novel compounds. In this study, we have identified an undefined dehydrogenase GOX1969 with no known substrate and defined structural similarities to outer membrane biogenesis protein BamB in E. coli K12. Furthermore, we demonstrate that GOX1969 is capable of complementing bamB knockout phenotypes in E. coli K12. Taken together, these findings enhance our understanding of G. oxydans physiology and expand the list of potential targets for future industrial strain design.