In the absence of chitobiose, expression of chiPQ is silenced by the ChiX small regulatory RNA (sRNA), which sequesters the ribosome binding site of the chiPQ mRNA by an antisense mechanism. In the presence of chitosugars, the chbBCARFG chitobiose operon is induced and acts as an RNA trap to degrade the constitutively expressed ChiX, leading to the translation of chiPQ. Chitobiose and chitotriose also induce chiP mRNA synthesis. ChiQ appears dispensable for growth on either chitobiose or chitotriose.