Microbial Degradation of Nicotinamide by a Strain Alcaligenes sp. P156
Microbial Degradation of Nicotinamide by a Strain Alcaligenes sp. P156
复制标题
产碱菌菌株对烟酰胺的微生物降解。
DOI：
10.1038/s41598-019-40199-0
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发表时间：
2019-03-06
影响因子：
4.6
通讯作者：
Yu, Hao
中科院分区：
文献类型：
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作者：
Hu, Chunhui;Zhao, Shuxue;Yu, Hao
一种新的产碱菌属 sp。菌株P156可以利用烟酰胺作为其唯一的碳、氮和能量来源，是在固体废物处理厂的土壤中富集和分离的。表征了烟酰胺的需氧生长和降解。从菌株P156基因组序列中进行序列比对，获得7个烟酰胺降解相关基因。克隆并异源表达了四个基因，命名为 naaA、naaD、naaE 和 naaF。烟酰胺降解是通过脱氨作用启动的，在烟酰胺酶 NaaA 的催化下形成烟酸，该酶与来自拟南芥的烟酰胺酶具有最高的氨基酸序列同一性 (27.2%)。烟酸转化为6-羟基烟酸，进一步氧化为2,5-二羟基吡啶(2,5-DHP)。然后，2,5-DHP 通过 Fe2+ 依赖性双加氧酶 NaaD 转化为环裂解产物 N-甲酰马来酰胺酸。 N-甲酰马来酰胺酸分别通过NaaE和NaaF通过马来酰胺酸和马来酸转化为富马酸。据我们所知，这是烟酰胺在细菌中完全微生物降解的第一份报告。烟酰胺被认为是研究吡啶类化合物微生物降解的模型化合物，菌株P156中烟酰胺降解相关基因的分布与报道的类似基因簇不同。因此，本研究有助于了解吡啶类化合物的降解。
A novel Alcaligenes sp. strain P156, which can utilize nicotinamide as its sole source of carbon, nitrogen and energy, was enriched and isolated from soil in a solid waste treatment plant. Aerobic growth and degradation with nicotinamide were characterized. Seven nicotinamide degradation-related genes were obtained by sequence alignment from the genome sequence of strain P156. Four genes, designated naaA, naaD, naaE and naaF, were cloned and heterologously expressed. Nicotinamide degradation is initiated by deamination to form nicotinic acid catalyzed by the nicotinamidase NaaA, which shares highest amino acid sequence identity (27.2%) with nicotinamidase from Arabidopsis thaliana. Nicotinic acid is converted to 6-hydroxynicotinic acid, which is further oxidized to 2,5-dihydroxypyridine (2,5-DHP). 2,5-DHP is then transformed to a ring-cleavage product, N-formylmaleamic acid, by an Fe2+ dependent dioxygenase NaaD. N-formylmaleamic acid is transformed to fumaric acid through maleamic acid and maleic acid by NaaE and NaaF, respectively. To our knowledge, this is the first report of the complete microbial degradation of nicotinamide in bacteria. Nicotinamide is considered as a model compound for the study of microbial degradation of pyridinic compounds, and the nicotinamide degrading related genes in strain P156 were distributed differently from the reported similar gene clusters. Therefore, this study contribute to the knowledge on the degradation of pyridinic compounds.