Functional analysis of the leader peptide of the yeast gene CPA1 and heterologous regulation by other fungal peptides

The 25-amino-acid leader peptide present at the 5' end of yeast CPA1 mRNA i s responsible for the translational repression of that gene by arginine. We show here that the active domain of the yeast peptide is highly specific a nd extends over amino acids 6-23. The region between amino acids 6-21 is we ll conserved between similar peptides present upstream of CPA1-homologous g enes in other fungi. The Neurospora crassa arg-2 peptide represses the expr ession of CPA1, whereas the peptide from Aspergillus nidulans has only a we ak regulatory effect. Such results suggest that the N- and C-terminal amino acids of the peptide may influence its regulatory activity. We also show t hat the transcription start sites of CPA1 are not modified when the cells a re grown in the presence of arginine, nor in a strain carrying an inactive peptide.