Seminar: "Disentangling the Origins of Alpha and Beta Carboxysomes in Cyanobacteria" - Carolina Martinez-Gutierrez

Enigma Seminar Series

Disentangling the Origins of Alpha and Beta Carboxysomes in Cyanobacteria

Carolina Martinez-Gutierrez

Assistant Professor, Early Life & Microbial Evolution Lab, UC Santa Barbara

Cyanobacteria are an ancient and diverse phylum of photosynthetic microorganisms that occupy a broad diversity of habitats on modern ecosystems. Cyanobacteria have played a relevant role in geochemistry of Earth because dioxygen, a byproduct of photosynthesis, led to the Great Oxidation Event (GOE) and the oxygenation of the atmosphere and the ocean. Modern Cyanobacteria are informally classified as alpha or beta depending on their type of ribulose-1,5-bisphosate (RuBisCo) and carboxysome, a microbial microcompartment responsible for the concentration of carbon dioxide within the cell. To date, it remains enigmatic why, if functionally similar, Cyanobacteria have two distinct types of carboxysomes. In this talk, I will present phylogenomic evidence that points to the independent origins and evolutionary histories of alpha- and beta-carboxysomes in Cyanobacteria. I will introduce hypotheses on the origin of carboxysomes in Cyanobacteria, why they acquired a new type of carboxysome, and what has maintained both types of carboxysome evolutionary isolated since their origin. Moreover, I will go over a novel phylogenomic pipeline that allows the reconstruction of the deep evolutionary history of bacterial and archaeal lineages.