mutated OR or OL operator DNA sequences that have a different thermostability, method of selecting the mutated operator sequences, vectors and nucleic acid sequences containing the mutated operator sequences thereof

摘要

A process for selecting new PR- or PL-operator sequences of lambdoid phages which, compared to wild-type sequences, have a different thermo-stability for the binding of a repressor, wherein: (a) A DNA cassette is prepared which contains a selection gene under the operative control of an expression control sequence comprising at least one OR or OL operator sequence from a lambdoid phage and a promoter; (b) The operator DNA sequence is subjected to a mutagenesis; and (c) The mutated operator DNA sequences are analysed. In addition, disclosed are mutated PR- or PL- operator sequences and their use for temperature-regulated expression of genes and for producing improved vaccines.