RWTH-Logo
 
Institut für Organische Chemie
 
AK Weinhold
 

Area of Research:

The current research interest of Professor Elmar Weinhold and his coworkers is in the field of bioorganic chemistry. The research is focussed on the relationship between structure and activity of DNA-modifying enzymes, such as DNA methyltransferases. After incorporation of well designed modifications into the DNA substrate or the cofactor by organic synthesis and modification of the enzymes by molecular biology techniques, the results of these structural changes are analysed by various biochemical and biophysical methods and used for the design or selection of new catalytic properties and inhibitors. For example, the DNA methyltransferase M.TaqI catalyses the transfer of the activated methyl group from the cofactor S-adenosyl-L-methionine (1) to the amino group of adenine within the double-stranded 5'-TCGA-3' DNA sequence 2.
With such a reaction the question arises how M.TaqI reaches its target base which is deeply buried in the DNA helix. Using duplex oligodeoxynucleotides containing the unnatural, fluorescent 2-aminopurine base at the target position 3, we could demonstrate that M.TaqI, like other DNA methyltransferases, flips its target base out of the DNA helix for catalysis [1,2]. This result is supported by an enhanced reactivity of a thymine base at the target position 4 towards permanganate oxidation in the presence of M.TaqI [3]. In addition, photochemical cross-linking of M.TaqI and duplex oligodeoxynucleotides containing 5-iodouracil at the target position 5 were used to locate the binding site for the extrahelical target base [4].
Recently, we determined the three-dimensional structure of M.TaqI in complex with its DNA substrate and a synthetic, non-reactive cofactor analogue by X-ray crystallography. The structure not only suggests how base flipping is achieved by M.TaqI but also implies the catalytic mechanism of M.TaqI and other DNA methyltransferases [5].
Our mechanistic and structural studies of DNA methyltransferases are also of biotechnological importance. Replacement of the side chain of the natural cofactor 1 with an aziridine group leads to the new cofactor 6, which is sequence-specifically coupled with DNA by M.TaqI [6]. By attaching interesting reporter groups at the 8 position of the new cofactor we could obtain a system for Sequence-specific Methyltransferase-Induced Labelling of DNA (SMILing DNA), which could find interesting applications in molecular biology, medical diagnosis and nano-biotechnology

Selected recent references:

  1. B. Holz, E. Weinhold in Bioorganic Chemistry: Highlights and New Aspects (Eds.: U. Diederichsen, T. K. Lindhorst, B. Westermann, L. Wessjohann), Wiley-VCH, Weinheim, 1999, pp. 337-345.
  2. B. Holz, S. Klimasauskas, S. Serva, E. Weinhold, Nucleic Acids Res. 1998, 26, 1076-1083.
  3. S. Serva, E. Weinhold, R. J. Roberts, S. Klimasauskas, Nucleic Acids Res. 1998, 26, 3473-3479.
  4. B. Holz, N. Dank, J. E. Eickhoff, G. Lipps, G. Krauss, E. Weinhold, J. Biol. Chem. 1999, 274, 15066-5072.
  5. K. Goedecke, M. Pignot, R. S. Goody, A. J. Scheidig, E. Weinhold, Nature Structural Biology, in press.
  6. M. Pignot, C. Siethoff, M. Linscheid, E. Weinhold, Angew. Chem. 1998, 110, 3050-3053; Angew. Chem. Int. Ed. 1998, 37, 2888-2891.
Original design by: Christian Dalhoff
Last modified : 21.10.2005 (S.Peters)