REGULATION AND ORGANIZATION OF THE GROE AND DNAK OPERONS IN EUBACTERIA

groEL and dnaK are the most highly conserved protein-coding genes know n. Most groEL operons and several dnaK and dnaJ operons contain a high ly conserved inverted repeat (IR) sequence in their regulatory region. So far, this IR has been found only as part of the groE, dnaK and dna J operons and genes. In most cases, the IR is part of the operon trans cript, and is involved in the regulation of expression at both the DNA and the mRNA levels. A detailed analysis of groE and dnaK operons ind icates that the organization of the groE operons is highly conserved. They contain only the groES and groEL genes and always in the same ord er. In contrast, the organization of the dnaK operons has changed duri ng evolution: genes have been added and deleted from it, and the gene order within the operon is variable.