The Architecture of Cyanobacteria, Archetypes of Microbial Innovation

Abstract

With an impressive and unparalleled evolutionary history spanning over two billion years, cyanobacteria have evolved to thrive in a diverse range of habitats and numerically dominate vast regions, such as the open oceans. Impacts of this microbial lineage on our planet have been far-reaching: ancestors of extant cyanobacteria had a pivotal role not only in the establishment of oxygen as a major component of the atmosphere, but in the rise of embryophytic algae and land plants. The evolution of innovative cellular structure and function in response to abiotic and biotic selection pressures has resulted in a striking diversity in cyanobacteria. Given the fact that the relationship between form and function is complex, and that cellular structures are often multifunctional and dynamic, this review uses a comparative approach in understanding how biological functions or strategies impact cellular architecture. Notably, differences existing in cellular architecture among genera, and even between strains of the same genus, often reflect evolutionary innovations that have permitted a group to flourish in a particular environment. This review also addresses how a conserved cellular feature, namely the compartmentalization of key functions, has promoted metabolic flexibility and survival. This compartmentalization involves structures such as the internal membranes, heterocysts and carboxysomes, and has permitted the functioning and integration of diverse, and at times, incompatible, processes in a single cell. With heightened interest in utilizing photosynthetic organisms to address global challenges in food and energy resources, research on this remarkable lineage will undoubtedly continue to inform, as well as inspire.