Department of Bacteriology, University of Wisconsin-Madison, Madison, Wisconsin, USA.
J Bacteriol. 2013 Aug;195(16):3603-9. doi: 10.1128/JB.00463-13. Epub 2013 Jun 7.
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.
RidA（YjgF/YER057c/UK114）蛋白家族成员在生命领域广泛保守。在体外，这些蛋白可脱氨 3-或 4-碳烯胺，这些烯胺是吡哆醛 5′-磷酸（PLP）依赖的丝氨酸/苏氨酸脱水酶的机制中间体生成。三碳烯胺 2-氨基丙烯酸可通过已在体外很好地描述的机制形成共价加合物，从而使一些酶失活。RidA 的生化活性表明，ridA 突变菌株的表型是由反应性烯胺代谢物的积累引起的。本文中的数据表明，在沙门氏菌的 ridA 突变菌株中，稳定的 2-氨基丙烯酸（2-AA）/PLP 加合物在生物合成丙氨酸消旋酶 Alr 上形成，表明体内存在 2-氨基丙烯酸。这项研究证实了代谢酶产生的 2-氨基丙烯酸的有害影响，并强调了 RidA 淬灭这种反应性代谢物的必要性。
