The gene encoding cAMP receptor protein is required for competence development in Haemophilus influenzae Rd.

The Haemophilus influenzae Rd strain JG87 contains a single mini-Tn10kan insertion that causes a deficiency in the development of competence for genetic transformation. The DNA fragment containing this insertion mutation, as well as the wild-type locus, was cloned, mapped, and sequenced. The sequence contained an open reading frame for a protein of 224 amino acids with a predicted Mr of 25,152. The deduced protein sequence showed strong similarity to the Escherichia coli cAMP receptor protein. The E. coli crp gene cloned on a multicopy plasmid was shown to fully complement the competence-deficient phenotype of the mutant strain; thus, the H. influenzae gene was named crp. These results suggest that H. influenzae cAMP-cAMP receptor protein complex functions to regulate one or more promoters essential for the development of competence in H. influenzae Rd. Features of a gene upstream of H. influenzae crp that is homologous to the E. coli ttk gene are also described.