Fig. 7

Updated model for the regulation of the stoichiometry of cellulosomal components in vivo. The cip-cel operon is transcribed by its promoter into the primary cip-cel mRNA, but most transcripts are prematurely terminated by an internal terminator at IR5. Cleavage signals located in the six intergenic regions are specifically recognized by endoribonucleases, resulting in cleavage of the primary transcript into several secondary transcripts. Stability of these secondary transcripts varies widely due to their distinct structures at both ends, which convey resistance to exoribonuclease degradation