Characterization of an l-Ascorbate Catabolic Pathway with Unprecedented Enzymatic Transformations.
Characterization of an l-Ascorbate Catabolic Pathway with Unprecedented Enzymatic Transformations.
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具有前所未有的酶促转化的 L-抗坏血酸分解代谢途径的表征。
DOI：
10.1021/jacs.9b09863
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发表时间：
2020
影响因子：
15
通讯作者：
Gerlt,JohnA
中科院分区：
文献类型：
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作者：
Stack,TylerMM;Morrison,KatelynN;Dettmer,ThomasM;Wille,Brendan;Kim,Chan;Joyce,Ryan;Jermain,Madison;Naing,YadanarThan;Bhatti,Khadija;Francisco,BrianSan;Carter,MichaelS;Gerlt,JohnA
l-抗坏血酸（维生素C）在我们的饮食和环境中无处不在。本文报道了嗜热罗尔斯通氏菌（Ralstonia eutropha）H16（Cupriavidus necatorATCC 17699）通过一种新的分解代谢途径以l-抗坏血酸为唯一碳源。RNaseq鉴定了8个候选分解代谢基因，并利用序列相似性网络和基因组邻域网络对编码蛋白的功能进行了预测，预测结果得到了基因缺失突变体体外分析和体内生长表型的证实。预测具有WD 40样折叠的蛋白质催化前所未有的二苯甲酸重排，涉及羧酸酯基团的迁移以形成2-羧基-1-来苏糖内酯;内酯被酰胺水解酶超家族的成员水解以产生2-羧基-1-来苏糖酸酯。氧化脱羧酶的PdxA家族的成员催化使用NAD+催化的新型脱羧。产物l-来复酸通过先前表征的途径分解代谢为α-酮戊二酸。这种途径存在于数百种细菌中，包括病原体铜绿假单胞菌和鲍曼不动杆菌。
l-Ascorbate (vitamin C) is ubiquitous in both our diet and the environment. Here we report thatRalstonia eutrophaH16 (Cupriavidus necatorATCC 17699) usesl-ascorbate as sole carbon source via a novel catabolic pathway. RNaseq identified eight candidate catabolic genes, sequence similarity networks, and genome neighborhood networks guided predictions for function of the encoded proteins, and the predictions were confirmed byin vitroassays andin vivogrowth phenotypes of gene deletion mutants.l-Ascorbate, a lactone, is oxidized and ring-opened by enzymes in the cytochromeb561and gluconolactonase families, respectively, to form 2,3-diketo-l-gulonate. A protein predicted to have a WD40-like fold catalyzes an unprecedented benzilic acid rearrangement involving migration of a carboxylate group to form 2-carboxy-l-lyxonolactone; the lactone is hydrolyzed by a member of the amidohydrolase superfamily to yield 2-carboxy-l-lyxonate. A member of the PdxA family of oxidative decarboxylases catalyzes a novel decarboxylation that uses NAD+catalytically. The product,l-lyxonate, is catabolized to α-ketoglutarate by a previously characterized pathway. The pathway is found in hundreds of bacteria, including the pathogensPseudomonas aeruginosaandAcinetobacter baumannii.