FcrX coordinates cell cycle and division during free-living growth and symbiosis by a ClpXP-dependent mechanism.

is a soil bacterium that establishes a nitrogen-fixing symbiosis within root nodules of legumes. In this symbiosis, undergoes a drastic cellular change leading to a terminally differentiated form, called bacteroid, characterized by genome endoreduplication, increased cell size, and high membrane permeability. Bacterial cell cycle (mis)regulation is at the heart of this differentiation process.

Sinorhizobium meliloti Functions Required for Resistance to Antimicrobial NCR Peptides and Bacteroid Differentiation.

Legumes of the genus have a symbiotic relationship with the bacterium Sinorhizobium meliloti and develop root nodules housing large numbers of intracellular symbionts. Members of the odule-specific ysteine-ich peptide (NCR) family induce the endosymbionts into a terminal differentiated state. Individual cationic NCRs are antimicrobial peptides that have the capacity to kill the symbiont, but the nodule cell environment prevents killing.