Bacterial microcompartments (BMCs) are bacterial organelles involved in enzymatic processes, such as carbon fixation, choline, ethanolamine and propanediol degradation, and others. Formed of a semi-permeable protein shell and an enzymatic core, they can enhance enzyme performance and protect the cell from harmful intermediates. With the ability to encapsulate non-native enzymes, BMCs show high potential for applied use. For this goal, a detailed look into shell form variability is significant to predict shell adaptability. Here we present four novel 3D cryo-EM maps of recombinant Klebsiella pneumoniae GRM2 BMC shell particles with the resolution in range of 9 to 22 Å and nine novel 2D classes corresponding to discrete BMC shell forms. These structures reveal icosahedral, elongated, oblate, multi-layered and polyhedral traits of BMCs, indicating considerable variation in size and form as well as adaptability during shell formation processes.

• Klíčová slova
• GRM2, Klebsiella pneumoniae, bacterial microcompartments, cryo-EM,
• MeSH
• bakteriální proteiny chemie   metabolismus   MeSH
• elektronová kryomikroskopie MeSH
• Klebsiella pneumoniae chemie   metabolismus   ultrastruktura   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• bakteriální proteiny MeSH

Bacterial microcompartments (BMCs) are prokaryotic organelles consisting of a protein shell and an encapsulated enzymatic core. BMCs are involved in several biochemical processes, such as choline, glycerol and ethanolamine degradation and carbon fixation. Since non-native enzymes can also be encapsulated in BMCs, an improved understanding of BMC shell assembly and encapsulation processes could be useful for synthetic biology applications. Here we report the isolation and recombinant expression of BMC structural genes from the Klebsiella pneumoniae GRM2 locus, the investigation of mechanisms behind encapsulation of the core enzymes, and the characterization of shell particles by cryo-EM. We conclude that the enzymatic core is encapsulated in a hierarchical manner and that the CutC choline lyase may play a secondary role as an adaptor protein. We also present a cryo-EM structure of a pT = 4 quasi-symmetric icosahedral shell particle at 3.3 Å resolution, and demonstrate variability among the minor shell forms.

• MeSH
• bakteriální proteiny genetika   metabolismus   MeSH
• cholin metabolismus   MeSH
• elektronová kryomikroskopie MeSH
• genetické lokusy MeSH
• Klebsiella pneumoniae cytologie   enzymologie   genetika   ultrastruktura   MeSH
• lyasy genetika   metabolismus   MeSH
• organely enzymologie   ultrastruktura   MeSH
• rekombinantní proteiny genetika   metabolismus   MeSH
• syntetická biologie MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• bakteriální proteiny MeSH
• cholin MeSH
• lyasy MeSH
• rekombinantní proteiny MeSH