In the Absence of RidA, Endogenous 2-Aminoacrylate Inactivates Alanine Racemases by Modifying the Pyridoxal 5′-Phosphate Cofactor
In the Absence of RidA, Endogenous 2-Aminoacrylate Inactivates Alanine Racemases by Modifying the Pyridoxal 5′-Phosphate Cofactor
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DOI：
10.1128/jb.00463-13
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发表时间：
2013-08-01
影响因子：
3.2
通讯作者：
Downs, Diana M.
中科院分区：
文献类型：
--
作者：
Flynn, Jeffrey M.;Downs, Diana M.
RidA（YjgF/YER 057 c/UK 114）蛋白家族的成员在生命的各个领域中广泛保守。在体外，这些蛋白质使3-或4-碳烯胺脱氨，所述烯胺作为吡哆醛5 '-磷酸（PLP）依赖性丝氨酸/苏氨酸脱氢酶的机械中间体产生。三碳烯胺2-氨基丙烯酸酯可以通过形成共价加合物来抑制一些酶，其机制已经在体外得到了很好的表征。RidA的生化活性表明，ridA突变株的表型是由反应性烯胺代谢产物的积累引起的。本文的数据显示，在肠道沙门氏菌的ridA突变菌株中，在生物合成丙氨酸消旋酶Alr上形成稳定的2-氨基丙烯酸酯（2-AA）/PLP加合物，表明体内存在2-氨基丙烯酸酯。这项研究证实了代谢酶产生的2-氨基丙烯酸酯的有害作用，并强调需要RidA淬灭这种反应性代谢产物。
Members of the RidA (YjgF/YER057c/UK114) protein family are broadly conserved across the domains of life. In vitro, these proteins deaminate 3- or 4-carbon enamines that are generated as mechanistic intermediates of pyridoxal 5'-phosphate (PLP)-dependent serine/threonine dehydratases. The three-carbon enamine 2-aminoacrylate can inactivate some enzymes by forming a covalent adduct via a mechanism that has been well characterized in vitro. The biochemical activity of RidA suggested that the phenotypes of ridA mutant strains were caused by the accumulation of reactive enamine metabolites. The data herein show that in ridA mutant strains of Salmonella enterica, a stable 2-aminoacrylate (2-AA)/PLP adduct forms on the biosynthetic alanine racemase, Alr, indicating the presence of 2-aminoacrylate in vivo. This study confirms the deleterious effect of 2-aminoacrylate generated by metabolic enzymes and emphasizes the need for RidA to quench this reactive metabolite.