Shell component of a type 2A encapsulin nanocompartment. Forms encapsulin nanocompartments about 24 nm in diameter from 60 monomers. Probably encapsulates at least cysteine desulfurase (CyD) and allows passage of cysteine into its interior, probably involved in sulfur metabolism. Homooligomeric (PubMed:9596734). The encapsulin nanocompartment is formed by 60 subunits; monomers form pentamers which assemble to form shells. There are 12 charged pores where the pentamers meet as well as 3-fold axis channels and dimer channels (By similarity). Has 4 domains; an N-terminal arm not found in the type 1 subfamily, a discontinuous peripheral domain (P), an elongated loop (E) and the discontinuous axial domain (A). Dominant antigen for this bacteria, could possibly used in vaccine formulation and/or for diagnosis. Belongs to the encapsulin family. Family 2A subfamily.