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Structure-function analysis of lipopeptide pheromones from the plant pathogen Ustilago maydis
1Institute for Genetics and Microbiology, Ludwig Maximilians University of Munich, Germany.
Molecular Genetics and Genomics : MGG
|November 19, 2002
Summary
Ustilago maydis uses lipopeptide pheromones for cell recognition during mating. Key amino acids in the a1 pheromone, particularly tyrosine 10, are crucial for its function and receptor binding.
Area of Science:
- Mycology
- Molecular Biology
- Biochemistry
Background:
- Ustilago maydis, a corn pathogen, requires cell mating for infection.
- Cell-cell recognition is mediated by lipopeptide pheromones (a1 and a2) encoded at the a mating type locus.
- Pheromones contain an S-prenylated cysteine methyl ester at the C-terminus.
Purpose of the Study:
- To analyze the structure-function relationship of synthetic a1 and a2 pheromones from Ustilago maydis.
- To identify critical amino acid residues and structural features of the a1 pheromone essential for biological activity.
Main Methods:
- Testing of truncated derivatives of a1 and a2 pheromones in a biological assay.
- Systematic amino acid substitution (alanine or D-amino acids) at each position of the a1 pheromone.
- Introduction of various natural and synthetic amino acids at position 10 of the a1 pheromone.
Main Results:
- Pheromone function is more sensitive to C-terminal than N-terminal truncations.
- Glycines at positions 5 and 9, proline at 7, and tyrosine at 10 are critical for a1 pheromone activity.
- An aromatic side chain at position 10 of a1 is necessary for function.
Conclusions:
- A proposed model suggests a cis peptide bond at proline 7 induces a beta turn, exposing tyrosine 10 for receptor binding.
- This structural feature likely contributes to the specificity of pheromone-receptor interactions in Ustilago maydis.