7MU1

Thermotoga maritima encapsulin shell

Summary for 7MU1

• Entry DOI: 10.2210/pdb7mu1/pdb
• EMDB information: 24001
• Descriptor: Maritimacin, FLAVIN MONONUCLEOTIDE (2 entities in total)
• Functional Keywords: encapsulin, ferritin-like protein, encflp, thermotoga, fmn, bacterial nanocompartment, virus like particle
• Biological source: Thermotoga maritima
• Total number of polymer chains: 1
• Total formula weight: 30825.96

Authors

LaFrance, B.J.,Nogales, E.,Savage, D.F. (deposition date: 2021-05-14, release date: 2021-11-24, Last modification date: 2024-05-29)

Primary citation

LaFrance, B.J.,Cassidy-Amstutz, C.,Nichols, R.J.,Oltrogge, L.M.,Nogales, E.,Savage, D.F.
The encapsulin from Thermotoga maritima is a flavoprotein with a symmetry matched ferritin-like cargo protein.
Sci Rep, 11:22810-22810, 2021

PubMed Abstract: Bacterial nanocompartments, also known as encapsulins, are an emerging class of protein-based 'organelles' found in bacteria and archaea. Encapsulins are virus-like icosahedral particles comprising a ~ 25-50 nm shell surrounding a specific cargo enzyme. Compartmentalization is thought to create a unique chemical environment to facilitate catalysis and isolate toxic intermediates. Many questions regarding nanocompartment structure-function remain unanswered, including how shell symmetry dictates cargo loading and to what extent the shell facilitates enzymatic activity. Here, we explore these questions using the model Thermotoga maritima nanocompartment known to encapsulate a redox-active ferritin-like protein. Biochemical analysis revealed the encapsulin shell to possess a flavin binding site located at the interface between capsomere subunits, suggesting the shell may play a direct and active role in the function of the encapsulated cargo. Furthermore, we used cryo-EM to show that cargo proteins use a form of symmetry-matching to facilitate encapsulation and define stoichiometry. In the case of the Thermotoga maritima encapsulin, the decameric cargo protein with fivefold symmetry preferentially binds to the pentameric-axis of the icosahedral shell. Taken together, these observations suggest the shell is not simply a passive barrier-it also plays a significant role in the structure and function of the cargo enzyme.

PubMed: 34815415
DOI: 10.1038/s41598-021-01932-w

Experimental method

ELECTRON MICROSCOPY (3.3 Å)