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Free keywords:
SCHERFFELIA-DUBIA PRASINOPHYCEAE; CHLAMYDOMONAS CELL-WALL; CRYOELECTRON
TOMOGRAPHY; ELECTRON TOMOGRAPHY; APPARATUS ACTIVITY; VITREOUS SECTIONS;
SCALE BIOGENESIS; EUKARYOTIC CELLS; MEMBRANE FLOW; POLYPHOSPHATEfocused ion beam; cryo-electron tomography; Chlamydomonas; Golgi;
glycosyltransferase;
Abstract:
We acquired molecular-resolution structures of the Golgi within its native cellular environment. Vitreous Chlamydomonas cells were thinned by cryo-focused ion beam milling and then visualized by cryo-electron tomography. These tomograms revealed structures within the Golgi cisternae that have not been seen before. Narrow trans-Golgi lumina were spanned by asymmetric membrane-associated protein arrays that had similar to 6-nm lateral periodicity. Subtomogram averaging showed that the arrays may determine the narrow central spacing of the trans-Golgi cisternae through zipper-like interactions, thereby forcing cargo to the trans-Golgi periphery. Additionally, we observed dense granular aggregates within cisternae and intracisternal filament bundles associated with trans-Golgi buds. These native in situ structures provide new molecular insights into Golgi architecture and function.
