Department of Biotechnology, University of Natural Resources and Applied Life Sciences, Muthgasse 18, 1190 Vienna, Austria.
J Biotechnol. 2010 Jan 15;145(2):120-9. doi: 10.1016/j.jbiotec.2009.11.004. Epub 2009 Nov 14.
Detoxification of the mycotoxin fumonisin B(1) comprises at least two enzymatic steps, an initial deesterification reaction, followed by deamination of the resulting hydrolyzed fumonisin B(1). In this study, two genes that are responsible for degradation of fumonisin B(1) by the bacterium Sphingopyxis sp. MTA144 were identified within a gene cluster, assumed to be associated with fumonisin degradation. The first gene encodes a protein which shows similarity to carboxylesterases, type B. The second gene encodes a polypeptide homologous to aminotransferases, class III. The two genes were isolated and expressed heterologously. The effect of the recombinant enzymes on fumonisin B(1) and hydrolyzed fumonisin B(1) was determined. The recombinant carboxylesterase was shown to catalyze the deesterification of fumonisin B(1) to hydrolyzed fumonisin B(1). The heterologously expressed aminotransferase was shown to deaminate hydrolyzed fumonisin B(1) in the presence of pyruvate and pyridoxal phosphate. We propose that the consecutive action of these two enzymes is sufficient for fumonisin B(1) detoxification. The results of this work provide a basis for the development of an enzymatic detoxification process for fumonisin B(1) in food and animal feed, especially under oxygen limited conditions, as they are found, e.g. in ensilaged forage or in the intestinal tract of animals.
真菌毒素伏马菌素 B(1) 的解毒至少包含两个酶促步骤，先是初始的去酯化反应，然后是水解伏马菌素 B(1) 的脱氨反应。在这项研究中，鉴定了一种假定与伏马菌素降解有关的基因簇内负责细菌 Sphingopyxis sp. MTA144 降解伏马菌素 B(1) 的两个基因。第一个基因编码的蛋白与羧酸酯酶 B 型相似。第二个基因编码的多肽与氨基转移酶 III 类同源。这两个基因被分离并在异源系统中表达。测定了重组酶对伏马菌素 B(1)和水解伏马菌素 B(1)的作用。结果表明，重组羧酸酯酶能够催化伏马菌素 B(1)的去酯化反应生成水解伏马菌素 B(1)。异源表达的氨基转移酶在丙酮酸和吡哆醛磷酸存在的情况下能够使水解伏马菌素 B(1)脱氨。我们推测这两种酶的连续作用足以使伏马菌素 B(1)解毒。这项工作的结果为在食品和动物饲料中开发伏马菌素 B(1)的酶解毒工艺提供了依据，特别是在氧气有限的条件下，例如青贮饲料或动物肠道中。
