Assembly in vitro of Rhodococcus jostii RHA1 encapsulin and peroxidase DypB to form a nanocompartment

RhodococcusjostiiRHA1 peroxidase DypB has been recently identified as a bacterial lignin peroxidase. The dypB gene is cotranscribed with a gene encoding an encapsulin protein, which has been shown in Thermotogamaritima to assemble to form a 60-subunit nanocompartment, and DypB contains a C-terminal sequence motif that is thought to target the protein to the encapsulin nanocompartment. R.jostiiRHA1 encapsulin protein was overexpressed in R.jostii RHA1, and purified as a high-Mr assembly (Mr>106). The purified nanocompartment could be disassembled to form a low-Mr species by treatment at pH3.0, and reassembled to form an assembly of similar size and shape, as assessed by dynamic light scattering. Recombinant DypB could be assembled invitro with monomeric encapsulin to form an assembly of similar size to the encapsulin-only nanocompartment, as assessed by gel filtration. The assembled complex showed enhanced lignin degradation activity per milligram of DypB present as compared with native DypB, as determined with a nitrated lignin UVvisible assay method. The measured stoichiometry of 8.6mol encapsulin/mol DypB in the complex was similar to the value of 10 predicted from the crystal structure. Structured digital abstract encapsulin and encapsulin bind by blue native page (View interaction) encapsulin and encapsulin bind by dynamic light scattering (View interaction)