Cloning and sequencing of the Haemophilus influenzae aroA gene

This study was designed to clone the aroA gene (encoding 5-enolpyruvylshikimate-3-phosphate synthase [EPSPS]) from Haemophilus influenzae using a mixed-primer polymerase chain reaction (PCR). The mixed primers were based on a back translation of previously reported blocks of amino acid homology between different cloned EPSPS proteins. The PCR-produced probe from H. influenzae DNA was used to identify a recombinant lambda phage from which the rest of H. influenzae aroA was subcloned and sequenced. The sequence of H. influenzae aroA is highly homologous to all other aroA genes sequenced to date. The upstream sequence of aroA, when translated, results in a protein with strong homology to the purN gene product, glycinamide ribonucleotide transformylase. The stop codon of the putative H. influenzae purN gene overlaps the start codon for H. influenzae aroA, suggesting that the two genes may form an operon and that they may be translationally coupled.