IDENTIFICATION BY PCR OF GENES ENCODING MULTIPLE RESPONSE REGULATORS

Environmental sensing in bacteria often involves the concerted action of sensor kinases and response regulators. Degenerate oligonucleotide primers were designed on the basis of amino acid similarity in the res ponse regulators of these two-component systems. The primers were used in PCR to specifically amplify an internal DNA segment corresponding to the receiver module domain from genes encoding response regulators. Amplification products of the expected size were obtained from 12 dif ferent Gram-positive and Gramnegative bacteria. Sequence analysis reve aled that 22 DNA fragments, which clearly originated from response reg ulator genes, were amplified from Escherichia coli, Agrobacterium tume faciens, Bacillus subtilis and Lactobacillus bulgaricus. In each of th ese four species the receiver module of putative response regulator ge nes, which do not seem to be related to any of the already characteriz ed genes, was identified. This simple and powerful method is therefore particularly useful for discovering new signal transduction systems w hich cannot be revealed by usual genetic studies.