Scientists map hidden bacterial motor
- Nature Microbiology researchers mapped the unusually complex flagellar motor of Campylobacter jejuni, a major foodborne pathogen, showing how extra scaffolds stabilize its movement machinery. - The team found an E ring of 17 FlgY homodimers plus spoke-and-cage structures that help recruit and support 17 torque-generating stator complexes. - Campylobacter causes common diarrheal illness, and C. jejuni accounts for almost 90% of human cases in CDC data. (cdc.gov)
Bacteria move with a tail called a flagellum, and that tail spins because a motor buried in the cell envelope turns like a rotary engine. In *Campylobacter jejuni*, researchers have now mapped that motor in much finer detail. (nature.com 1) (nature.com 2) *Campylobacter jejuni* is a common cause of diarrheal illness, usually linked to raw or undercooked poultry, and the Centers for Disease Control and Prevention says it causes almost 90% of human *Campylobacter* infections. It can also trigger complications including Guillain-Barré syndrome. (cdc.gov 1) (cdc.gov 2) (cdc.gov 3) Most textbook bacterial motors come from simpler species such as *Escherichia coli* and *Salmonella enterica*. *C. jejuni* carries a bulkier version built to generate more torque, which helps it move through thick, viscous environments. (nature.com 1) (nature.com 2) A 2025 paper used in situ cryogenic electron microscopy on *C. jejuni* minicells and resolved the motor to subnanometre scale. That study showed three large periplasmic disks and found that PflA-PflB assembly helps recruit FliL so the motor can hold more stator complexes at a wider radius. (nature.com) The January 9, 2026 paper pushed that map closer to complete. The authors reported an E ring made of 17 FlgY homodimers, a cage-like structure built from FcpMNO and PflD, and PflA-PflB interactions arranged in a spoke-rim pattern between the E ring and the cage. (nature.com) Those added parts act like braces around the motor. The paper says the scaffolds stabilize 17 torque-generating stator complexes, helping explain how *C. jejuni* builds one of the most elaborate flagellar motors seen in bacteria. (nature.com) (nature.com) The work also ties the motor to older machinery. The authors’ phylogenetic analysis suggests some of these extra structures have an ancient origin and that ancestors of Campylobacterota co-opted components from type IV pili, another bacterial surface machine. (nature.com) (nature.com) The papers do not report a new drug or a tested therapy. They provide a structural parts list for a pathogen’s movement system, which gives researchers specific proteins and assemblies to probe in future studies. (nature.com) (nature.com) For now, the main result is mechanical: *C. jejuni* does not run on the stripped-down motor biologists long used as the standard model. It runs on a reinforced version whose extra rings, spokes and cage can now be named and placed. (nature.com) (nature.com)
