| Summary: | To study the role of adenylate cyclase in competence development, a partial
clone of the Haemophilus influenzae cya gene was isolated by complementation of a
Acya Escherichia coli strain. Adenylate cyclase was believed to have a role in
competence development because it catalyzes production of adenosine 3':5'-cyclic
monophosphate (cAMP), a known regulator of competence. To prove that
adenylate cyclase was essential for competence development, transposon
mutagenesis was used to form the cya- H. influenzae strain RR668, with an
insertion in the region of cya coding for the catalytic domain. Characterization of
this mutant has shown that cya is an essential gene for spontaneous late log
competence, and for competence induced by starvation conditions. The partial
preliminary sequence of the cloned gene had significant amino acid homology to
the cya genes from enteric bacteria and the more closely related bacterium
Pasteurella multocida. Examination of the cya sequence also revealed a possible
CRP binding site (with 55% homology to the consensus Escherichia coli site) located
upstream of the putative start codon GTG. The presence of the presumptive CRP
site indicated that H. influenzae, like other bacterial species, may regulate cAMP
synthesis by CRP mediated feedback repression of transcription. If the start codon
was correctly identified as GTG, then this is the first known bacterial cya gene to use
GTG as a start codon instead of ATG or TTG.
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