Ethanolamine-induced assembly of microcompartments is required for <i>Fusobacterium nucleatum</i> virulence

The oral anaerobe <i>Fusobacterium nucleatum</i> can spread to distal internal organs, such as the colon and placenta, thereby promoting the development of colorectal cancer and inducing preterm birth, respectively. Yet, how this opportunistic pathogen adapts to the various metabolically distinct host cellular niches remains poorly understood. We demonstrated here that this microbe assembles specialized metabolic organelles, termed bacterial microcompartments (BMCs), to utilize environmental ethanolamine (EA) as a key environmental nutrient source. The formation of <i>F. nucleatum</i> BMCs, containing BMC shell proteins EutLM1M2N, is controlled by a two-component system, EutV-EutW, responsive to EA. Significantly, this ability of <i>F. nucleatum</i> to form BMCs in response to EA is crucial for its pathogenicity evidenced by the fact that the genetic disruption of BMC formation reduces fusobacterial virulence in a mouse model of preterm birth.