1.S.7.  The Bacterial/Archaeal Nanocompartment Encapsulin Shell Protein2 (BANC-SP2) Family

These proteins may be distantly homologous or similar in size to those in TC family 1.S.6, They are all called 'encapsulins'.  Pores in encapsulins have been engineered as a general strategy to improve protein-based enzyme nanoreactor performance (Kwon et al. 2024). Cargo enzymes include ferroxidases involved in iron storage, peroxidases involved in oxidative stress resistance, cysteine desulfurases involved in sulfur storage, and terpene cyclases involved in terpenoid biosynthesis (Dutcher et al. 2024). Enzyme encapsulation inside encapsulin shells can convey a number of distinct advantages, such as the formation of an optimized reaction environment, enzyme co-localization, intermediate sequestration, and the exclusion of unwanted proteins and molecules. The encapsulin shell may also serve to regulate cargo enzymes by modulating the flux of small molecule metabolites through its pores whilst stabilizing the oligomeric state of enzymatic cargo. Encapsulins are found in at least 35 prokaryotic phyla and have been classified into four distinct families based on operon structure and shell protein phylogeny (6, 33). Family 2, the most abundant class of encapsulins, is further subdivided into Family 2A and Family 2B based on the absence or presence, respectively, of a putative cyclic nucleotide binding domain (CBD) inserted into the E-loop of the HK97 fold encapsulin shell protein (Dutcher et al. 2024). 

 

 

 


This family belongs to the Encapsulin Shell Protein (Enc) (of Bacterial/Archaeal Nanocompartments) Superfamily.
 

References:

Akita, F., K.T. Chong, H. Tanaka, E. Yamashita, N. Miyazaki, Y. Nakaishi, M. Suzuki, K. Namba, Y. Ono, T. Tsukihara, and A. Nakagawa. (2007). The crystal structure of a virus-like particle from the hyperthermophilic archaeon Pyrococcus furiosus provides insight into the evolution of viruses. J. Mol. Biol. 368: 1469-1483.
Dutcher, C.A., M.P. Andreas, and T.W. Giessen. (2024). A two-component quasi-icosahedral protein nanocompartment with variable shell composition and irregular tiling. bioRxiv.
He, D., C. Piergentili, J. Ross, E. Tarrant, L.R. Tuck, C.L. Mackay, Z. McIver, K.J. Waldron, D.J. Clarke, and J. Marles-Wright. (2019). Conservation of the structural and functional architecture of encapsulated ferritins in bacteria and archaea. Biochem. J. 476: 975-989.
Kwon, S., M.P. Andreas, and T.W. Giessen. (2024). Pore engineering as a general strategy to improve protein-based enzyme nanoreactor performance. bioRxiv.
Namba, K., K. Hagiwara, H. Tanaka, Y. Nakaishi, K.T. Chong, E. Yamashita, G.E. Armah, Y. Ono, Y. Ishino, T. Omura, T. Tsukihara, and A. Nakagawa. (2005). Expression and molecular characterization of spherical particles derived from the genome of the hyperthermophilic euryarchaeote Pyrococcus furiosus. J Biochem 138: 193-199.
Examples:

TC#NameOrganismal TypeExample
1.S.7.1.1

Encapsulin nanocompartment cargo protein EncC of 130 aas.

Encapsulin of Myxococcus xanthus


  
 
1.S.7.1.2

Encapsulin B, EncB, of 158 aas and 0 TMSs.

EncB of Myxococcus xanthus

 
1.S.7.1.3

Ferritin-like-encapsulin shell fusion protein, EncP1, of 345 aas is a fusion of the shell and cargo protein of a type 1 encapsulin nanocompartment (Akita et al. 2007). The nanocompartment is probably involved in iron storage. Expression in E. coli generates spherical particles about 30 nm in diameter (Namba et al. 2005). The purified N-terminus has ferroxidase activity (He et al. 2019).

Encapsulin of Pyrococcus furiosus

 
1.S.7.1.4

Encapsulated ferritin-like protein, Fer, of 131 aas and a moderately hydrophilic character throughout its sequence.  It may function in iron transport and storage.

Fer of Haliangium ochraceum

 
1.S.7.1.5

Type 1 encapsulin shell protein of 287 aas, EncA. This protein has the viral capsid protein, HK97-fold.

 

EncA of Myxococcus xanthus