Cell polarity control by an unconventional G-protein complex in bacteria
Year: 2026
Type: article
Abstract: In Myxococcus xanthus , cell polarity and motility are regulated by the small GTPase MglA and its associated regulators, MglB, a potential GTPase Activating Protein and the RomRX complex, a potential Guanine nucleotide Exchange Factor. However, recent results have questioned the exact function of these regulators. Using a new type of fluorescent nucleotides for fluorescence-based anisotropy, we first demonstrate that RomRX does not function as a GEF but as an effector that binds strictly to MglA GTP . Secondly, based on an enzymology model, we found that MglB functions as a weak catalyst, unlike typical GAPs, and requires additional factors to dissociate from MglA. We demonstrate that RomRX, and specifically RomR, effectively competes with MglA by sequestering MglB. This low affinity interaction is still permissive for GAP activity but sufficient to partition these proteins in vivo as indicated by a biomimetic assay in oil emulsion droplets reconstituting these interactions in a cell-sized environment. These results suggest a new model for cell polarity where RomRX exerts a dual function, targeting MglA GTP to the pole via its effector function and preventing its accumulation at the lagging pole by destabilizing the MglA-MglB complex.
Source: Nature Communications
Institutions: Centre National de la Recherche Scientifique, Aix-Marseille Université, Institut de Neurophysiopathologie, Institut de Microbiologie de la Méditerranée, Institut de Biologie du Développement Marseille, Laboratoire de Chimie Bactérienne, Laboratoire d'Ingénierie des Systèmes Macromoléculaires, Architecture et Fonction des Macromolécules Biologiques, Université de Bretagne Occidentale, Laboratoire de Mathématiques de Bretagne Atlantique, National University of Singapore, Mechanobiology Institute, Bridging Mechanobiology and Medicine
Language: English
Subfield: Genetics
Domain: Life Sciences
Open Access status: gold
Estimated APC paid: $6,990
OpenAlex ID: W4403967508