IDENTIFICATION OF THE CONSERVED CODING SEQUENCES OF 3 CHITIN SYNTHASEGENES IN FONSECAEA-PEDROSOI

Primers having designs based on highly conserved stretches in the dedu ced amino acid sequences of chitin synthase (CHS) genes were used in P CR reactions to amplify 600 bp and 366 bp products from the genomic DN A of three major causal agents of chromoblastomycosis. Cloning and seq uencing of the PCR products of one of these fungi, Fonsecaea pedrosoi, identified three CHS sequences designated as FpCHS1, FpCHS2 and FpCHS 3. FpCHS1 and FpCHS2 were homologous to regions of CHS1 and CHS2 of Sa ccharomyces cerevisiae, and their derived amino acid sequences fell in to chitin synthase classes I and II, respectively. FpCHS3 was homologo us to a region of the CAL1/CSD2 gene of S. cerevisiae, which codes for the chitin synthase three (Chs3) enzyme in that fungus. Phylogenetic trees constructed using the deduced amino acid sequences of PCR-amplif ied CHS products from many fungi clustered F. pedrosoi with other dema tiaceous fungi, providing new molecular evidence for the genetic relat edness of these organisms. The identification of these CHS genes in F. pedrosoi will facilitate future studies of the functional roles of ch itin synthases in the unique in vivo dimorphism exhibited by chromobla stomycotic fungi.