2026/03/05 by Christopher A. Azaldegui, Hema M. Swasthi, Longhua Hu +5 · 1 voice
Environmental Science · Biochemistry, Genetics and Molecular Biology · #Microbial Fuel Cells and Bioremediation #Bacterial Genetics and Biotechnology #Photosynthetic Processes and Mechanisms
paper · doi:10.64898/2026.03.03.709431
Abstract Carboxysomes are bacterial microcompartments that drive efficient carbon fixation in autotrophic bacteria. Critical to their function and inheritance is their spatial organization by the ParA-type ATPase, McdA, and its partner protein, McdB. Here, we investigate the α-carboxysome McdAB system in Halothiobacillus neapolitanus using biochemical assays, quantitative fluorescence imaging, and mathematical modeling. We find that, unlike most ParA-type ATPases, the ATPase activity of McdA is only stimulated by DNA rather than by its partner protein McdB. Despite this difference, McdB conserves the ability to displace McdA from DNA, suggesting that ATP hydrolysis and DNA unbinding by McdA are not strictly coupled. Together with its ability to diffuse while bound to DNA, McdA forms gradients on the nucleoid that prevent carboxysome aggregation via a Brownian ratchet mechanism. Overall, these findings reveal key differences in a ParA-type ATPase that may be specific for the spatial organization of protein-based organelles in bacteria.