The information stored in the DNA is essential to every form of life. It is therefore crucial that the information is copied accurately, without the introduction of any mistakes. The process of copying DNA, called DNA replication, is a complicated process that requires many different proteins to work together. How this is achieved is not well understood. We therefore study DNA replication in the model organism E. coli. For this we use structural methods such cryo-electron microscopy and protein crystallography to determine how the different proteins interact with one another. We also use biochemical and single molecule methods to determine how the sequential steps of DNA replication are organized in time. We also study DNA replication in the bacterium Mycobacterium tuberculosis (Mtb). Mtb causes tuberculosis that kills an estimated 1.5 million people world-wide each year, making Mtb the deadliest pathogen, even before HIV. We study DNA replication in Mycobacterium tuberculosis to find new targets that can be used to develop new antibiotics for the treatment of TB. New antibiotics are urgently needed as resistance to antibiotics is increasing at an alarming rate in Mtb, but also other pathogenic bacteria. We have already found a new target and are currently screening for chemical inhibitors that will be further developed into novel antibiotics.