Structure and function of the diadenylate cyclase CdaA

The spread of antibiotic resistance in many different bacteria is a global health problem. The World Health Organization (WHO) has therefore made the search for new antibiotics and new targets for antibiotics one of its main goals. Should we fail to bring new antibiotics or new forms of therapy to the market, even banal bacterial infections could be life-threatening. To survive a bacteria must precisely control the amount of water and salts that are taken up and released. A weak point that has not been exploited for the development of antibiotics yet. The protein diadenylate cyclase CdaA produces a molecule (c-di-AMP), that is used in many bacteria to regulate this uptake and release. For this reason, inhibiting the diadenylate cyclase CdaA could be a new way of killing bacteria. The aim of our project is to understand the function of the CdaA diadenylate cyclase together with two regulatory proteins CdaR and GlmM. In order to develop a good antibiotic we need to know how the complex of CdaA, CdaR and GlmM looks like and what factors influence its activity. For this we will first elucidate the three-dimensional structure of the complex of CdaA, CdaR and GlmM. In addition, we will develop a system that will match the environment in the bacterial cell as much as possible to test the activity of the complex under different conditions. Structure determination is based on a combination of three different structural biology techniques: X-ray crystallography, cryo-electron microscopy and nuclear magnetic resonance. Due to the different strengths and weaknesses in structure determination, a combination of the individual techniques is most promising. The activity tests are carried out in bacterial membranes, as it allows us to maintain the membrane proteins CdaA and CdaR in their natural environment. Based on these functional tests in bacterial membranes, we will develop a screening for the search for new antibiotics. All experiments described here are conducted at three sites: X-ray crystallography, functional testing and screening at i3S Porto under the supervision of Dr. João Morais- Cabral, cryo-electron microscopy at the University of Groningen under the supervision of Dr. Cristina Paulino and nuclear magnetic resonance at the University of Vienna under the supervision of Prof. Robert Konrat.