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Molecular Genetics and Genomics

, Volume 268, Issue 3, pp 362–370 | Cite as

Structure-function analysis of lipopeptide pheromones from the plant pathogen Ustilago maydis

  •  Z. Szabó
  •  M. Tönnis
  •  H. Kessler
  •  M. Feldbrügge
Original Paper

Abstract.

Mating of two haploid cells is a prerequisite for the successful infection of corn by the pathogenic fungus Ustilago maydis. Cell-cell recognition is mediated by small lipopeptide pheromones. Genes encoding pheromone precursors as well as pheromone receptors are located in the a mating type locus. Two pheromones are known, the tridecapeptide a1 and the nonapeptide a2, both of which contain an S-prenylated cysteine methyl ester at the C-terminus. It has previously been shown that synthetic pheromones are active in a biological test system. Here, we used the same assay to perform a detailed analysis of synthetic a1 and a2 pheromones. Testing of truncated derivatives of a1 and a2 revealed that in both cases the pheromone function is less sensitive to N-terminal than to C-terminal truncations. Replacement of each amino acid in the a1 pheromone by either alanine or the corresponding D-amino acids revealed that four positions are important for function: the two central glycines (positions 5 and 9), proline at position 7 and tyrosine at position 10. By introducing different naturally occurring as well as synthetic amino acids at position 10, we demonstrate that the presence of an aromatic side chain at this position is necessary for function. We propose a model in which a cis peptide bond at proline 7 favours the formation of a type II′ β turn of the a1 pheromone backbone with glycine 9 in position i+1 (where i refers to the first position of the β turn). As a result, tyrosine 10, at position i+2 of the turn, would be highly exposed and could be inserted into a structurally well-defined binding pocket of the receptor. The latter may represent an important facet of receptor specificity.

Synthetic pheromones Type II′ β turn Seven-transmembrane receptor Mfa1 Mfa2 

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Copyright information

© Springer-Verlag 2002

Authors and Affiliations

  •  Z. Szabó
    • 1
  •  M. Tönnis
    • 2
  •  H. Kessler
    • 2
  •  M. Feldbrügge
    • 1
  1. 1.Institute for Genetics and Microbiology, Ludwig Maximilians University of Munich, Maria-Ward-Str. 1a, 80638 München, Germany
  2. 2.Institute for Organic Chemistry and Biochemistry, Technical University of Munich, Lichtenberg Str. 4, 85747 Garching, Germany

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