Mycobacterium tuberculosis ferritin: a suitable workhorse protein for cryo-EM development

Abril Gijsbers, Yue Zhang, Ye Gao, Peter J. Peters, Raimond B. G. Ravelli*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review


The use of cryo-EM continues to expand worldwide and calls for good-quality standard proteins with simple protocols for their production. Here, a straightforward expression and purification protocol is presented that provides an apoferritin, bacterioferritin B (BfrB), from Mycobacterium tuberculosis with high yield and purity. A 2.12 angstrom resolution cryo-EM structure of BfrB is reported, showing the typical cage-like oligomer constituting of 24 monomers related by 432 symmetry. However, it also contains a unique C-terminal extension (164-181), which loops into the cage region of the shell and provides extra stability to the protein. Part of this region was ambiguous in previous crystal structures but could be built within the cryo-EM map. These findings and this protocol could serve the growing cryo-EM community in characterizing and pushing the limits of their electron microscopes and workflows.

Original languageEnglish
Pages (from-to)1077-1083
Number of pages7
JournalActa Crystallographica. Section D: Structural Biology
Publication statusPublished - 1 Aug 2021


  • Mycobacterium tuberculosis
  • cryo-EM
  • expression and purification protocols
  • ferritin
  • single-particle analysis

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