Correlated cryogenic fluorescence microscopy and electron cryo-tomography shows that exogenous TRIM5a can form hexagonal lattices or autophagy aggregates in vivo

Stephen D. Carter, João I. Mamede, Thomas J. Hope, Grant J. Jensen*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

Members of the tripartite motif (TRIM) protein family have been shown to assemble into structures in both the nucleus and cytoplasm. One TRIM protein family member, TRIM5α, has been shown to form cytoplasmic bodies involved in restricting retroviruses such as HIV-1. Here we applied cryogenic correlated light and electron microscopy, combinedwith electron cryo-tomography, to intactmammalian cells expressing YFP-rhTRIM5α and found the presence of hexagonal nets whose arm lengths were similar to those of the hexagonal nets formed by purified TRIM5a in vitro. We also observed YFP-rhTRIM5α within a diversity of structures with characteristics expected for organelles involved in different stages of macroautophagy, including disorganized protein aggregations (sequestosomes), sequestosomes flanked by flat double-membraned vesicles (sequestosome:phagophore complexes), sequestosomes within double-membraned vesicles (autophagosomes), and sequestosomes within multivesicular autophagic vacuoles (amphisomes or autolysosomes). Vaults were also seen in these structures, consistent with their role in autophagy. Our data 1) support recent reports that TRIM5a can form both well-organized signaling complexes and nonsignaling aggregates, 2) offer images of the macroautophagy pathway in a near-native state, and 3) reveal that vaults arrive early in macroautophagy.

Original languageEnglish (US)
Pages (from-to)29702-29711
Number of pages10
JournalProceedings of the National Academy of Sciences of the United States of America
Volume117
Issue number47
DOIs
StatePublished - Nov 24 2020

Keywords

  • Autophagy
  • Cryo-CLEM/ECT
  • Endoplasmic reticulum
  • Hexagonal nets
  • TRIM5α-body

ASJC Scopus subject areas

  • General

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