TRANSCRIPTIONAL CONTROL OF THE CELLULASE GENES IN TRICHODERMA-REESEI

The expression of the cellulase transcripts of Trichoderma reesei is c ontrolled by the nature of the energy carbon sources used in the cultu re medium, Cellulose and the soluble disaccharide sophorose, but not g lycerol or glucose, act as inducers, Evidence is presented suggesting that a low constitutive extracellular cellulolytic system catalyzes th e formation of a soluble inducer from cellulose, and this inducer trig gers the expression of the cellulase transcripts. This basal and cellu lose-induced expression of the cellobiohydrolase I mRNAs (cbhl), the m ajor member of the cellulase system, is transcriptionally controlled b y two independent cis-acting DNA regions, In addition, expression of t he cbhl transcript is influenced by the physiological state of the mit ochondria and this sensitivity is controlled through the 5'-flanking D NA sequence of this gene.