Publications

• Degradation of fumonisin B1 by the consecutive action of two bacterial enzymes.

  Heinl S., Hartinger D., Thamhesl M., Vekiru E., Krska R., Schatzmayr G., Moll W.-D., Grabherr R.

  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 Sphingop ... >> More

  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. << Less

  J. Biotechnol. 145:120-129(2010) [PubMed] [EuropePMC]

  This publication is cited by 1 other entry.

• Enzyme characteristics of aminotransferase FumI of Sphingopyxis sp. MTA144 for deamination of hydrolyzed fumonisin B(1).

  Hartinger D., Schwartz H., Hametner C., Schatzmayr G., Haltrich D., Moll W.D.

  Fumonisins are carcinogenic mycotoxins that are frequently found as natural contaminants in maize from warm climate regions around the world. The aminotransferase FumI is encoded as part of a gene cluster of Sphingopyxis sp. MTA144, which enables this bacterial strain to degrade fumonisin B(1) and ... >> More

  Fumonisins are carcinogenic mycotoxins that are frequently found as natural contaminants in maize from warm climate regions around the world. The aminotransferase FumI is encoded as part of a gene cluster of Sphingopyxis sp. MTA144, which enables this bacterial strain to degrade fumonisin B(1) and related fumonisins. FumI catalyzes the deamination of the first intermediate of the catabolic pathway, hydrolyzed fumonisin B(1). We used a preparation of purified, His-tagged FumI, produced recombinantly in Escherichia coli in soluble form, for enzyme characterization. The structure of the reaction product was studied by NMR and identified as 2-keto hydrolyzed fumonisin B(1). Pyruvate was found to be the preferred co-substrate and amino group receptor (K (M) = 490 μM at 10 μM hydrolyzed fumonisin B(1)) of FumI, but other α-keto acids were also accepted as co-substrates. Addition of the co-enzyme pyridoxal phosphate to the enzyme preparation enhanced activity, and saturation was already reached at the lowest tested concentration of 10 μM. The enzyme showed activity in the range of pH 6 to 10 with an optimum at pH 8.5, and in the range of 6°C to 50°C with an optimum at 35°C. The aminotransferase worked best at low salt concentration. FumI activity could be recovered after preincubation at pH 4.0 or higher, but not lower. The aminotransferase was denatured after preincubation at 60°C for 1 h, and the residual activity was also reduced after preincubation at lower temperatures. At optimum conditions, the kinetic parameters K (M) = 1.1 μM and k (cat) = 104/min were determined with 5 mM pyruvate as co-substrate. Based on the enzyme characteristics, a technological application of FumI, in combination with the fumonisin carboxylesterase FumD for hydrolysis of fumonisins, for deamination and detoxification of hydrolyzed fumonisins seems possible, if the enzyme properties are considered. << Less

  Appl. Microbiol. Biotechnol. 91:757-768(2011) [PubMed] [EuropePMC]