Novel fungal transcriptional activators, Cmr1p of Colletotrichum lagenarium and Pig1p of Magnaporthe grisea, contain Cys2His2 zinc finger and Zn(II)2Cys6 binuclear cluster DNA-binding motifs and regulate transcription of melanin biosynthesis genes in a developmentally specific manner

Colletotrichum lagenarium and Magnaporthe grisea are plant pathogenic fungi that produce melanin during the appressorial differentiation stage of coni dial germination and during the late stationary phase of mycelial growth. H ere, we report the identification of genes for two unique transcription fac tors, CMR1 (Colletotrichum melanin regulation) and PIG1 (pigment of Magnapo rthe), that are involved in melanin biosynthesis. Both Cmr1p and Pig1p cont ain two distinct DNA-binding motifs, a Cys2His2 zinc finger motif and a Zn( II)2Cys6 binuclear cluster motif. The presence of both these motifs in a si ngle transcriptional regulatory protein is unique among known eukaryotic tr anscription factors. Deletion of CMR1 in C. lagenarium caused a defect in m ycelial melanization, but not in appressorial melanization. Also, cmr1 Delt a mutants do not express the melanin biosynthetic structural genes SCD1 and THR1 during mycelial melanization, although the expression of these two ge nes was not affected during appressorial melanization.