{"title":"Metabolic role of a genetically conserved aldehyde dehydrogenase in bacterial assimilation of various primary amines","authors":"Tadashi Nakai , Naoya Miyagi , Kota Hisamura , Shoya Matsuba , Kanji Nishimoto , Emi Nakai , Katsuyuki Tanizawa , Toshihide Okajima","doi":"10.1016/j.abb.2025.110387","DOIUrl":null,"url":null,"abstract":"<div><div>Primary amines such as <em>n</em>-butylamine and 2-phenylethylamine serve as good nitrogen, carbon, and energy sources for bacterial growth. In many Gram-negative bacterial species, these amines are first oxidized by a periplasmic enzyme, quinohemoprotein amine dehydrogenase (QHNDH), encoded in an operon termed ‘<em>qhp</em>’, consisting of eight genes (<em>qhpABCDEFGR</em>). A gene predicted to encode an aldehyde dehydrogenase is also highly conserved in the vicinity of the <em>qhp</em> operon. In this study, we found that a 5′-upstream region of the aldehyde dehydrogenase gene in <em>Paracoccus denitrificans</em> has a high promoter activity that responds to <em>n</em>-butylamine supplementation in the culture medium, indicating co-regulation with the <em>qhp</em> genes by the transcriptional regulator QhpR. Hence, we designate this gene as the ninth member of the <em>qhp</em> operon, <em>qhpH</em>. Disruption of <em>qhpH</em> in <em>P. denitrificans</em> neither affected bacterial growth on primary amines, nor impaired QHNDH activity, suggesting the presence of another constitutive aldehyde dehydrogenase(s) compensating for the defect of <em>qhpH</em>. Nevertheless, heterologous expression of <em>qhpH</em> along with the eight <em>qhp</em> genes in an amine non-assimilating bacterium, <em>Rhodobacter sphaeroides</em>, significantly enhanced the growth on <em>n</em>-butylamine, as compared to the slow growth without <em>qhpH</em>. The recombinant QhpH purified from <em>Escherichia coli</em> cells showed high aldehyde dehydrogenase activities toward various aldehydes. These findings demonstrate that the <em>qhpH</em> gene encodes an aldehyde dehydrogenase with broad substrate specificity and is evolutionarily conserved with the <em>qhp</em> operon to play a role in an efficient metabolism of various primary amines in Gram-negative bacteria.</div></div>","PeriodicalId":8174,"journal":{"name":"Archives of biochemistry and biophysics","volume":"768 ","pages":"Article 110387"},"PeriodicalIF":3.8000,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Archives of biochemistry and biophysics","FirstCategoryId":"99","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0003986125001006","RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"BIOCHEMISTRY & MOLECULAR BIOLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
Primary amines such as n-butylamine and 2-phenylethylamine serve as good nitrogen, carbon, and energy sources for bacterial growth. In many Gram-negative bacterial species, these amines are first oxidized by a periplasmic enzyme, quinohemoprotein amine dehydrogenase (QHNDH), encoded in an operon termed ‘qhp’, consisting of eight genes (qhpABCDEFGR). A gene predicted to encode an aldehyde dehydrogenase is also highly conserved in the vicinity of the qhp operon. In this study, we found that a 5′-upstream region of the aldehyde dehydrogenase gene in Paracoccus denitrificans has a high promoter activity that responds to n-butylamine supplementation in the culture medium, indicating co-regulation with the qhp genes by the transcriptional regulator QhpR. Hence, we designate this gene as the ninth member of the qhp operon, qhpH. Disruption of qhpH in P. denitrificans neither affected bacterial growth on primary amines, nor impaired QHNDH activity, suggesting the presence of another constitutive aldehyde dehydrogenase(s) compensating for the defect of qhpH. Nevertheless, heterologous expression of qhpH along with the eight qhp genes in an amine non-assimilating bacterium, Rhodobacter sphaeroides, significantly enhanced the growth on n-butylamine, as compared to the slow growth without qhpH. The recombinant QhpH purified from Escherichia coli cells showed high aldehyde dehydrogenase activities toward various aldehydes. These findings demonstrate that the qhpH gene encodes an aldehyde dehydrogenase with broad substrate specificity and is evolutionarily conserved with the qhp operon to play a role in an efficient metabolism of various primary amines in Gram-negative bacteria.
期刊介绍:
Archives of Biochemistry and Biophysics publishes quality original articles and reviews in the developing areas of biochemistry and biophysics.
Research Areas Include:
• Enzyme and protein structure, function, regulation. Folding, turnover, and post-translational processing
• Biological oxidations, free radical reactions, redox signaling, oxygenases, P450 reactions
• Signal transduction, receptors, membrane transport, intracellular signals. Cellular and integrated metabolism.