In situ ribosome clustering and ultrastructure reorganization of polar tube proteins in germinated microsporidia polar tube

ABSTRACT: During host cell invasion, microsporidia translocate their entire cytoplasmic contents through a thin, hollow superstructure known as the polar tube. To achieve this, the polar tube transitions from a compact spring-like state inside the environmental spore to a long needle-like tube capable of longrange sporoplasm delivery. The unique mechanical properties of the building blocks of the polar tube allow for an explosive transition from compact to extended state and support the rapid cargo translocation process. The molecular and structural factors enabling this ultrafast process and the ultrastructural changes during cargo delivery remain a mystery. Here, we employ light microscopy and in situ cryo-electron tomography to visualize multiple ultrastructural states of the polar tube, allowing us to evaluate the kinetics of its germination and characterize the underlying morphological transitions. We describe a cargo-filled state with a unique ordered arrangement of microsporidian ribosomes, which cluster along the thin tube wall, and an empty post-translocation state with a reduced diameter but a thicker wall. Together with endogenous compositional information from an affinity-purified polar tube, our work provides comprehensive novel data on the infection apparatus of microsporidia and demonstrates that ribosomes are efficiently transported through polar tubes in a spiral-like parallel arrangement.

INSTRUMENT(S): Orbitrap Exploris 480

ORGANISM(S): Vairimorpha Necatrix

SUBMITTER: Johannes Fuchs  

LAB HEAD: Himanshu Sharma

PROVIDER: PXD042571 | Pride | 2024-01-09

REPOSITORIES: Pride