Figure 1.

Distribution and diversity of Family 2B terpenoid encapsulins. (A) Encapsulin systems can be classified into four families. Enc: encapsulin shell protein. Adapted with changes with open access permission via a creative common license (https://creativecommons.org/licenses/by/4.0/).⁴ (B) Schematic of the known and putative roles of Family 2B encapsulins in terpene biosynthesis. The C5 prenyldiphosphate precursors DMAPP and IPP may be converted by encapsulated PTs into acyclic terpenoid precursors such as GPP, FPP, and GGPP. Acyclic terpenoid precursors can then be used by encapsulated TCs to produce cyclic terpenoid products. Encapsulin systems predicted to contain both TC and PT cargos may produce cyclic terpenoids directly using C5 prenyl diphosphate precursors. (C) Operon types and phylogenetic distribution of Family 2B encapsulins likely involved in terpene biosynthesis. A phylogenetic tree of 2416 terpene-associated Family 2B encapsulin shell proteins is shown. Family 2B accessions were obtained from the UniProt database by searching for accessions containing both PFAM annotations PF19307 and PF00027.³² Operon types were assigned using the EFI-GNT server to filter operons according to cargo type.³⁵ The phylogenetic tree was assembled via a custom workflow using the NGPhylogeny server where sequences were aligned using MAFFT, trimmed using BMGE, and trees assembled using FastTree with 200 bootstrap iterations.^36–40 The phylogenetic tree was then visualized and annotated using the ITOL server.⁴¹