Badreddine Douzi

- **Career Biography** Once he obtained a diploma in Biotechnology Engineering from University of Sfax in Tunisia, Badreddine Douzi moved to France to start a scientific career in the field of microbiology. He studied biochemistry, structural biology and molecular biology at the University of Aix-Marseille and obtained his Master degree. Then he earned a PhD in biochemistry and structural Biology under the supervision of Dr Romé Voulhoux and Dr Mariella Tegoni. His thesis work was dedicated to the study of molecular mechanisms underlying the assembly and function of a bacterial nanomachine called the type II secretion system (T2SS). Fascinated by these bacterial nanomachines, he was interested during his first postdoctorat, under the supervision of Dr Christian Cambillau, by studying a different secretion system called the type VI secretion system (T6SS) dedicated to the injection of toxins into neighboring cells. Then he moved to the University of British Columbia in the laboratory of Prof Franck Duong to study the molecular mechanisms that coordinates the translocation of colicins across the bacterial envelope. In 2015, he went back to France to join the team of Dr Romé Voulhoux as research associate to work on the T2SS, specifically on the assembly and function of the portal complex called the Secretin. After a short period on the laboratory of Dr Etienne Maisonneuve, Badreddine Douzi was appointed “Chargé de Recherche at the INRA in 2018 in the DynAMic laboratory. - **Research interest** Working on bacterial nanomachines since 2008, Badreddine Douzi main’s interests are to understand, at molecular levels, the mechanisms underlying the traffic of molecules across the bacterial envelope. The transport of molecules is orchestrated by a specialized bacterial apparatus called secretion systems. They are large macromolecular complexes dedicated to the transport of proteins and DNA to the extracellular milieu or directly to host cells. Among the nine secretion systems identified up to date, Badreddine Douzi is currently focused on the study of the assembly and function of the conjugative type IV secretion system (T4SS) in Gram + bacteria. These nanomachines are responsible for the transfer of mobile genetic elements between bacteria and consequently play a crucial role in horizontal gene transfer. He is using complementary approaches (genetics, molecular biology, biochemistry and structural biology) to understand how these nanomachines assembles on the bacterial envelope and ensure the DNA transfer.