THE ISOPRENOID PATHWAY - CLONING AND CHARACTERIZATION OF FUNGAL FPPS GENES

Farnesylpyrophosphate synthase (FPPS) is a key enzyme in isoprenoid bi osynthesis. Several classes of essential metabolites, including sterol s, quinones, carotenoids and gibberellins, are terpenoids with high bi ological activity. The structural gene for FPP synthase was isolated f rom two ascomycete fungi, Neurospora crassa and Giberella fujikuroi. A comparative analysis of the nucleotide sequences of both FPPS genes r evealed the presence of introns at the same positions al the 5' end of the coding regions. Furthermore, the most conserved region of the gen e was isolated from two other plant pathogenic fungi, Sphaceloma manih oticola and Claviceps purpurea, by PCR. Sequence analysis showed a hig h degree of similarity between the deduced proteins of all known FPP s ynthase genes. In contrast to animals, all analyzed fungi contain a si ngle copy of the gene, although FPP is the precursor for essential ste rol and quinone biosynthesis and secondary metabolites, such as gibber ellins, as well. Transcription analysis in different light regimes has shown that the FPPS genes in G. fujikuroi and N. crassa are not regul ated by light induction.