Fig. 1

Schematic overview of the content of the review. Different metabolic engineering strategies often render stressed cells (top). This translates into different stress symptoms observed in the cells (bottom). However, the nature of the stress responses, their interconnections and translation in stress symptoms remains a black box (middle). This box is often summarised in the term “metabolic burden”, without specifying the associated responses. The focus of this review is to explore this black box, more specifically for the (over)expression of (heterologous) (membrane) proteins. Gene structures are displayed according to the SBOL guidelines [6]