OMICS Research Group, Department of Biotechnology, Faculty of Applied and Computer Sciences, Vaal University of Technology, Vanderbijlpark 1911, South Africa.
BMC Biotechnol. 2021 Mar 1;21(1):18. doi: 10.1186/s12896-021-00677-8.
Aldehyde dehydrogenases are vital for aerobic hydrocarbon degradation and is involved in the last step of catalysing the oxidation of aldehydes to carboxylic acids. With the global increase in hydrocarbon pollution of different environments, these enzymes have the potential to be used in enzymatic bioremediation applications.
Fifteen fosmid clones with hydrocarbon degrading potential were functionally screened to identify dehydrogenase enzymes. Accordingly, the fosmid insert of the positive clones were sequenced using PacBio next generation sequencing platform and de novo assembled using CLC Genomic Work Bench. The 1233 bp long open reading frame (ORF) for DHY-SC-VUT5 was found to share a protein sequence similarity of 97.7% to short-chain dehydrogenase from E. coli. The 1470 bp long ORF for DHY-G-VUT7 was found to share a protein sequence similarity of 23.9% to glycine dehydrogenase (decarboxylating) (EC 1.4.4.2) from Caulobacter vibrioides (strain NA1000 / CB15N) (Caulobacter crescentus). The in silico analyses and blast against UNIPROT protein database with the stated similarity show that the two dehydrogenases are novel. Biochemical characterization revealed, that the highest relative activity was observed at substrate concentrations of 150 mM and 50 mM for DHY-SC-VUT5 and DHY-G-VUT7, respectively. The K values were found to be 13.77 mM with a V of 0.009135 μmol.min and 2.832 mM with a V of 0.005886 μmol.min for DHY-SC-VUT5 and DHY-G-VUT7, respectively. Thus, a potent and efficient enzyme for alkyl aldehyde conversion to carboxylic acid.
The microorganisms overexpressing the novel aldehyde dehydrogenases could be used to make up microbial cocktails for biodegradation of alkanes. Moreover, since the discovered enzymes are novel it would be interesting to solve their structures by crystallography and explore the downstream applications.
醛脱氢酶对于需氧烃类降解至关重要，并且参与催化醛氧化为羧酸的最后一步。随着不同环境中烃类污染的全球增加，这些酶有可能用于酶促生物修复应用。
从具有烃类降解潜力的 15 个 fosmid 克隆中进行了功能筛选，以鉴定脱氢酶。相应地，使用 PacBio 下一代测序平台对阳性克隆的 fosmid 插入物进行测序，并使用 CLC Genomic Work Bench 从头组装。发现长 1233bp 的开放阅读框（ORF）DHY-SC-VUT5 与大肠杆菌中的短链脱氢酶具有 97.7%的蛋白质序列相似性。发现长 1470bp 的 ORF DHY-G-VUT7 与 Caulobacter crescentus 中的甘氨酸脱氢酶（脱羧）（EC 1.4.4.2）（Caulobacter vibrioides （strain NA1000 / CB15N））具有 23.9%的蛋白质序列相似性。基于相似性的 UNIPROT 蛋白质数据库的计算机分析和比对表明，这两种脱氢酶是新颖的。生化特性表明，DHY-SC-VUT5 和 DHY-G-VUT7 的最佳相对活性分别在 150mM 和 50mM 的底物浓度下观察到。DHY-SC-VUT5 和 DHY-G-VUT7 的 K 值分别为 13.77mM 和 2.832mM，V 值分别为 0.009135μmol.min 和 0.005886μmol.min。因此，这是一种将烷基醛转化为羧酸的有效且高效的酶。
过表达新型醛脱氢酶的微生物可用于组成烷烃生物降解的微生物混合物。此外，由于发现的酶是新颖的，因此通过晶体学解决它们的结构并探索下游应用将是有趣的。
