Structure of a bacterial type III secretion system in contact with a host membrane in situ

Many bacterial pathogens of animals and plants use a conserved type III secretion system (T3SS) to inject virulence effector proteins directly into eukaryotic cells to subvert host functions. Contact with host membranes is critical for T3SS activation, yet little is known about T3SS architecture in this state or the conformational changes that drive effector translocation. Here we use cryo-electron tomography and sub-tomogram averaging to derive the intact structure of the primordial Chlamydia trachomatis T3SS in the presence and absence of host membrane contact. Comparison of the averaged structures demonstrates a marked compaction of the basal body (4 nm) occurs when the needle tip contacts the host cell membrane. This compaction is coupled to a stabilization of the cytosolic sorting platform– ATPase. Our findings reveal the first structure of a bacterial T3SS from a major human pathogen engaged with a eukaryotic host, and reveal striking ‘pump-action’ conformational changes that underpin effector injection

Attempting constitutional reform on the island microjurisdiction of Alderney

Research into state size and democracy has revealed that the very smallest states are more likely to be democratic than their larger counterparts. Being an island, as well as having a British colonial past, is also associated with a state’s observance of democratic measures. With these observations in mind, this article examines an unsuccessful attempt to reform the political and constitutional governance of the Channel Island of Alderney, a self-governing dependency of the British Crown. Why was political reform rejected on this island microjurisdiction? Was the post-Brexit agenda too crowded to permit reform? Did Alderney have other priorities? Might smallness itself be the explanation