Described are methods and means for metabolic engineering and improved product formation by a filamentous micro-organism or a low G+C gram-positive bacterium. Disclosed is that DasR and DasR binding sites play an important and universal role in the control of gene expression in micro-organisms. Based on this finding, provided are multiple useful applications, such as a method for regulating the expression of a gene of interest, a method for controlling metabolism, a method for decreasing undesired expression and many more. Moreover, provided are means that can be used to establish said methods: for example a micro-organism in which the DasR binding site in operable linkage with a particular gene has been modified to obtain increased or decreased expression of a protein (being a desired or undesired protein) encoded by said gene.