Geschmack ist vorhersagbar: Mit FlavorMiner. FlavorMiner heißt das Tool, das IPB-Chemiker und Partner aus Kolumbien jüngst entwickelt haben. Das Programm kann, basierend auf maschinellem Lernen (KI), anhand der…
Seit Februar 2021 bietet Wolfgang Brandt, ehemaliger Leiter der Arbeitsgruppe Computerchemie am IPB, sein Citizen Science-Projekt zur Pilzbestimmung an. Dafür hat er in regelmäßigen Abständen öffentliche Vorträge zur Vielfalt…
Wils, C. R.; Brandt, W.; Manke, K.; Vogt, T.;A single amino acid determines position specificity of an Arabidopsis thaliana CCoAOMT-like O-methyltransferaseFEBS Lett.587683-689(2013)DOI: 10.1016/j.febslet.2013.01.040
Caffeoyl‐coenzyme A O‐methyltransferase (CCoAOMT)‐like proteins from plants display a conserved position specificity towards the meta‐position of aromatic vicinal dihydroxy groups, consistent with the methylation pattern observed in vivo. A CCoAOMT‐like enzyme identified from Arabidopsis thaliana encoded by the gene At4g26220 shows a strong preference for methylating the para position of flavanones and dihydroflavonols, whereas flavones and flavonols are methylated in the meta‐position. Sequence alignments and homology modelling identified several unique amino acids compared to motifs of other CCoAOMT‐like enzymes. Mutation of a single glycine, G46 towards a tyrosine was sufficient for a reversal of the unusual para‐ back to meta‐O‐methylation of flavanones and dihydroflavonols.
Publikation
Lukačin, R.; Matern, U.; Hehmann, M.; Specker, S.; Vogt, T.;Corrigendum to “Cations modulate the substrate specificity of bifunctional class I O-methyltransferase from Ammi majus” [FEBS Lett. 577 (2004) 367-370]FEBS Lett.583855-855(2009)DOI: 10.1016/j.febslet.2009.01.050
Lukačin, R.; Matern, U.; Specker, S.; Vogt, T.;Cations modulate the substrate specificity of bifunctional class I O-methyltransferase from Ammi majusFEBS Lett.577367-370(2004)DOI: 10.1016/j.febslet.2004.10.032
Caffeoyl‐coenzyme A O‐methyltransferase cDNA was cloned from dark‐grown Ammi majus L. (Apiaceae) cells treated with a crude fungal elicitor and the open reading frame was expressed in Escherichia coli . The translated polypeptide of 27.1‐kDa shared significant identity to other members of this highly conserved class of proteins and was 98.8% identical to the corresponding O‐methyltransferase from parsley. For biochemical characterization, the recombinant enzyme could be purified to apparent homogeneity by metal‐affinity chromatography, although the recombinant enzyme did not contain any affinity tag. Based on sequence analysis and substrate specificity, the enzyme classifies as a cation‐dependent O‐methyltransferase with pronounced preference for caffeoyl coenzyme A, when assayed in the presence of Mg2+‐ions. Surprisingly, however, the substrate specificity changed dramatically, when Mg2+ was replaced by Mn2+ or Co2+ in the assays. This effect could point to yet unknown functions and substrate specificities in situ and suggests promiscuous roles for the lignin specific cluster of plant O‐methyltransferases.
Publikation
Vogt, T.;Regiospecificity and kinetic properties of a plant natural product O-methyltransferase are determined by its N-terminal domainFEBS Lett.561159-162(2004)DOI: 10.1016/S0014-5793(04)00163-2
A recently discovered, S‐adenosyl‐L ‐methionine and bivalent cation‐dependent O‐methyltransferase from the ice plant, Mesembryanthemum crystallinum , is involved in the methylation of various flavonoid and phenylpropanoid conjugates. Differences in regiospecificity as well as altered kinetic properties of the recombinant as compared to the native plant O‐methyltransferase can be attributed to differences in the N‐terminal part of the protein. Upon cleavage of the first 11 amino acids, the recombinant protein displays essentially the same substrate specificity as observed earlier for the native plant enzyme. Product formation of the newly designed, truncated recombinant enzyme is consistent with light‐induced accumulation of methylated flavonoid conjugates in the ice plant. Therefore, substrate affinity and regiospecificity of an O‐methyltransferase in vivo and in vitro can be controlled by cleavage of an N‐terminal domain.