DIFFERENTIAL EXPRESSION OF MULTIPLE EXO-CELLOBIOHYDROLASE I-LIKE GENES IN THE LIGNIN-DEGRADING FUNGUS PHANEROCHAETE-CHRYSOSPORIUM

The genome of Phanerochaete chrysosporium strain ME446 contains multiple, non-allelic, cellobiohydrolase I (CBHI)-like sequences, at least two of which are expressed in a cellulose-dependent manner. Each of the expressed genes contains two identically positioned introns within its coding region. The lengths and sequences of these introns are different and one is not excised from all transcripts, raising the possibility that subtly different protein products may be expressed from a common gene. Introns are also present upstream of both genes but these differ in number and position, as well as sequence and length. Endoglucanase-like sequences could not be identified and it is suggested that variant CBHI-like proteins may provide endoglucanase activity in this fungus.