For my Masters’ first year internship I studied the impact of DNA supercoiling on the gene expression and thus acting as a regulation factor. We investigated the statistical link between DNA supercoiling and the AT-content of bacterial promoters. We found that supercoiling sensitive genes that are induced by DNA relaxation had a higher AT-content than those repressed by relaxation. We also defined an interval of 6nt on which no contact with a regulation or transcription protein is known. The AT-content on this interval may act as a discriminant factor into the differential reponse in front of supercoiling regulation.