Microbial Metabolism of β-Peptides

Microbial metabolism of β-peptides

β-Amino acids and their derivatives occur as building blocks in a wide variety of natural products. For example, they are part of natural linear or cyclic peptides, like bestatin or microcystin, or non-peptidic, pharmaceutically active substances, like the cancer drug taxol. On the other hand, no natural peptides which are solely composed of β-amino acids are known so far, but many β-peptides consisting of β-amino acid residues with proteinogenic side-chains have been synthesized and described during the last decade. β-Peptides show a high potential for the development of new, pharmaceutically active substances which function as peptidomimetics, since these unusual peptides are highly stable against common proteases and peptidases, they can mimic α-peptides and show antimicrobial, hemolytic, and antiproliferative activities.

We are interested to investigate if the stability of β-peptides against peptidases and proteases is as absolute as claimed in many studies. Growth experiments were performed with bacterial isolates and soil samples to broaden the spectrum of enzymes which might be able to degrade β-peptides. The β-tripeptide H-β-HVal-β-HAla-β-H-Leu-OH was used as model substrate and served as carbon and nitrogen source. The results of these tests provided evidence that enzymes of microbial origin exist which can degrade β-peptides. Considering the ecological aspect, this fact is of high importance, because β-peptides used in medicinal chemistry or materials sciences eventually enter the environment. Until now, we could isolate one bacterial strain which is capable of growing on the β-tripeptide. Currently, our work focuses on the degradation pathway of the β-tripeptide, the responsible enzymes and the formed metabolites.

Publications

• Geueke,B., Namoto,K., Agarkova,I., Perriard,J.C., Kohler,H.P.E., and Seebach,D. "Bacterial cell penetration by b³-oligohomoarginines: Indications for passive transfer through the lipid bilayer." Chembiochem 6, no. 6 (2005): 982-985.

• Geueke,B., Namoto,K., Seebach,D., and Kohler,H.P.E. "A novel b-peptidyl aminopeptidase (BapA) from strain 3-2W4 cleaves peptide bonds of synthetic b-tri- and b-dipeptides." Journal of Bacteriology 187, no. 17 (2005): 5910-5917.

• Geueke,B., and Kohler,H.-P.E. "Bacterial b-peptidyl aminopeptidases: On the hydrolytic degradation of b-peptides." Applied Microbiology and Biotechnology, submitted (2006).

• Heck,T., Limbach,M., Geueke,B., Zacharias,M., Gardiner,J., Kohler,H.-P.E., and Seebach,D. "Enzymatic degradation of b- and mixed a,b-oligopeptides." Chemistry and Biodiversity, submitted (2006).

• Geueke,B., Busse,H.J., Fleischmann,T., Kämpfer,P., and Kohler,H.-P.E., "Description of Sphingosinicella xenopeptidilytica sp. nov., a b-peptide degrading strain, and emended descriptions of the genus Sphingosinicella and the species Sphingosinicella microcystinivorans." International Journal of Systematic and Evolutionary Microbioly, in print (2006).

• Geueke,B., Heck,T., Limbach,M., Seebach,D., and Kohler,H.-P.E. "Bacterial b-peptidyl aminopeptidases with unique substrate specificities for b- and mixed b/a-oligopeptides. " FEBS Journal, accepted (2006).

Posters & oral presentations

• 1st Swiss Microbial Ecology Meeting, Neuchâtel, Uni Mail, September 23-24, 2004; Oral presentation: Birgit Geueke, Hans-Peter E. Kohler; Microbial degradation of b-peptides

• 1st International Conference on Environmental, Industrial and Applied Microbiology (BioMicroWorld-2005) Badajoz, Spain, March 15-18, 2005; Poster: Birgit Geueke, Hans-Peter E. Kohler; Hydrolysis of b-peptides by the novel aminopeptidase BapA from Sphingomonas sp. 3-2W4

• Swiss Society for Microbiology, Annual Assembly, Genève, Uni Mail, March 31 - April 1, 2005; Poster: Birgit Geueke, Kenji Namoto, Dieter Seebach, Hans-Peter E. Kohler; Bacterial cell penetration by b-oligo-homoarginines; Poster: Birgit Geueke, Hans-Peter E. Kohler; Hydrolysis of b-peptides by an aminopeptidase from Sphingomonas sp. 3-2W4
  

• 12th European Congress on Biotechnology, Copenhagen, Denmark, August 21-24, 2005; Poster: Birgit Geueke, Dieter Seebach, Hans-Peter E. Kohler; The b-peptidyl aminopeptidase BapA from strain 3-2W4 cleaves synthetic b-peptides

• Swiss Society for Microbiology, Annual Assembly, University of Lausanne, Switzerland; March 7-8, 2006; Oral presentation: Birgit Geueke, Tobias Heck, Michael Limbach, Dieter Seebach, Hans-Peter E. Kohler; b-Peptides: Novel pharmaceuticals of future pollutants?

• International Symposium on Environmental Biotechnology, UFZ Leipzig, Germany; July 9-13, 2006; Oral presentation: Birgit Geueke, Tobias Heck, Michael Limbach, Dieter Seebach, Hans-Peter E. Kohler; Degradation of b-peptides by novel b-peptidyl aminopeptidases from environmental isolates

• Biocat 2006, 3rd International Congress on Biocatalysis, Hamburg University of Technology, Hamburg, Germany; September 3-7, 2006; Oral presentation: Birgit Geueke, Tobias Heck, Michael Limbach, Dieter Seebach, Hans-Peter E. Kohler; On the enzymatic degradation of b-peptides

• 2nd Swiss Microbial Ecology Meeting, Bellinzona, September 28-29, 2006; Oral presentation: Birgit Geueke, Tobias Heck, Michael Limbach, Dieter Seebach, Hans-Peter E. Kohler; On the enzymatic degradation of b-peptides

Theses

• Eva Schaub, Department of Chemistry, University Duisburg-Essen, Germany, March 2005 - July 2005; Bachelor Thesis: Microbial degradation of b-peptides: Growth and genetic experiments with strains Y2 and 3-2W4

• Tobias Heck, Department of Biology, University Tübingen, May 2005 - March 2006; Diploma Thesis: Novel aminopeptidases for biodegradation and synthesis of b-peptides

• Birgit Weissenböck, Fachhochschule Wels, Austria, November 2005 - August 2006; Diploma Thesis: Isolierung und Expression von neuen Transaminase-Genen