Snapshots of native pre-50S ribosomes reveal a biogenesis factor network and evolutionary specialization

Ribosome biogenesis is a fundamental multi-step cellular process that culminates in the formation of the ribosomal subunits, whose production and modifications are steered and regulated by numerous biogenesis factors. In this study, we analyze unperturbed native prokaryotic ribosome biogenesis by isolating bona fide pre-50S subunits by using an E. coli strain, producing the affinity tagged biogenesis factor ObgE from its native gene locus. Our integrative structural approach reveals a network of interacting biogenesis factors consisting of YjgA, RluD, RsfS and ObgE on the immature pre-50S subunit. In addition, our study provides mechanistic insight into how the GTPase ObgE, in concert with other biogenesis factors, facilitates the maturation of the 50S functional core and reveals both conserved and divergent evolutionary features of ribosome biogenesis between prokaryotes and eukaryotes.