Geology Club Seminar

A defining feature of cells is their ability to spatially organize their cytosolic milieu into specialized compartments. Many bacteria possess protein-based organelles that compartmentalize enzymes with metabolic activities that are incompatible with the rest of the cell. One example is the carboxysome, a bacterial microcompartment, which compartmentalizes RuBisCO and carbonic anhydrase to optimize CO2 fixation. Although bacterial microcompartments are well-studied, another class of proteinaceous organelles, known as bacterial nanocompartments, remain poorly understood. Recent bioinformatic evidence has revealed that there may be many distinct families of these nanocompartments widespread throughout prokaryotic phyla with novel cargo proteins and physiological functions. Here, we have identified a novel bacterial nanocompartment family found in the freshwater cyanobacteria Synechococcus elongatus PCC 7942. We have shown that this nanocompartment encapsulates a cysteine desulfurase cargo via an N-terminal targeting sequence and have implicated its potential role in sulfur starvation response. Using Cryo-EM, we have determined the structure of this nanocompartment to 2.2Å resolution. Further investigation into the physiological role of this nanocompartment may reveal a novel response pathway to sulfate limitation.