The genetic basis of natural competence in filamentous Cyanobacteria

• Applicant: Professorin Dr. Tal Dagan
• Subject Area: Metabolism, Biochemistry and Genetics of Microorganisms
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 456882089

DNA acquisition by lateral transfer plays a major role in the evolution of prokaryotic organisms. Recombination plays a role in selective sweeps through the population, while lateral gene transfer has important implications to microbial adaptation and evolutionary innovation. Our focus in this grant proposal is on one DNA transfer mechanism – natural transformation – where DNA acquisition depends on the ability of the recipient cell to actively transport DNA from the environment into the cytoplasm, which is termed natural competence. The prevalence of natural competence in bacteria suggests that natural competence may be beneficial for bacteria, although the nature of the benefit is still debated and three possibilities are discussed in the literature 1) metabolic advantage (i.e., food), 2) availability of template for DNA repair, and 3) increased genetic diversity due to recombination. Here we propose to research the mechanisms of natural competence in filamentous cyanobacteria. Cyanobacteria inhabit diverse ecosystems including aquatic and soil habitats, extreme environments, as well as host-associated habitats. Marine cyanobacteria are important factors in the global carbon flux and the marine nitrogen cycle. Several cyanobacteria species are important for applications in the food industry and biotechnology. The investigation of natural competence in cyanobacteria was so far focused on unicellular model organisms. Nonetheless, our preliminary results indicate that natural competence is abundant in filamentous and heterocystous cyanobacteria, thus they open up possibilities to research several key questions: are there additional cyanobacteria that are naturally competent and are thus accessible for genetic modification using natural transformation? Are there additional, so far unrecognized genes, which are involved in natural competence in filamentous cyanobacteria? How is natural competence integrated into the cellular and metabolic processes in filamentous cyanobacteria? How is natural competence regulated within a cyanobacterial filament? In this proposal we aim to study in depth the mechanisms of natural competence in filamentous cyanobacteria and their regulation at the level of the population and the individual filament. Expanding the inventory of known competent organisms will enable us to pinpoint common mechanisms that are involved in natural competence across cyanobacterial species. Studying the physiology of natural competence in detail is furthermore expected to supply clues as for the advantages and disadvantages of natural competence in cyanobacteria. Focusing on filamentous cyanobacteria will further contribute to our understanding of the implications of DNA acquisition in multicellular bacteria. Our research is expected to have implications not only to cyanobacteria research and biotechnological applications, but also to the research of natural competence and DNA acquisition by transformation in other bacterial phyla.

• DFG Programme: Research Grants