Process for integration of a chosen gene on the chromosome of a bacterium using Mu transposons

DETAILED DESCRIPTION One aim of the invention is to describe a method for amplifying and stably fixing the copies of chosen genes in a microorganism with more flexibility and more reliability than was hitherto possible.
This aim as well as other objects of the invention, such as are envisaged hereafter, have been accomplished, for example, by providing the Escherichia coli bacterium with a transposable element having a wide host range and derived from the Mu phage, and in which the genes of the transposase cannot be expressed or are deleted.
Such a transposon is a defective transposon.
Under particular reversible genetic conditions which are easy to reproduce for organisms of the same genus or of a different genus, this transposon and the genes which can be introduced into it by genetic engineering technologycan be made to multiply inside the chromosome of the microorganism.
When the particular genetic conditions are removed, the various copies of the transposon remain fixed in a stable manner inside the chromosome.
The present invention relates to a process for integration of a chosen gene or of a specific DNA sequence (inside a bacterium) in a DNA sequence such as a chromosome or an episome, wherein: a) the said chosen gene or the chosen DNA sequence is cloned inside a defective transposon outside the essential parts of the transposon, b) the said transposon is integrated in the DNA sequence inside the bacterium.
More particularly, the process according to the invention is used to amplify the chosen copy number of genes in order to obtain a specific number of copies.
In this case the process according to the invention is a process for integration of a specific number of copies of a chosen gene or of a specific DNA sequence in a DNA sequence such as the chromosome or episome of a bacterium, wherein: a) the said chosen gene or the chosen DNA sequence is cloned inside a transposon outside the essential parts of the transposon, the said transposon being defective, b) the said transposon is integrated in the DNA sequence such as the chromosome or the episome of the said bacterium, c) the said defective transposon is complemented so as to be able to transpose several times and the complementation is then stopped after a specific number of transpositions