FIGURE 5.

Proposed model for role of RbgA in 50 S subunit maturation. RbgA interacts with the 45 S intermediate in the GTP-bound form and introduces conformational changes that further facilitate the binding of late ribosomal proteins such as L16, L27, and L36 (depicted by ovals). Binding of these proteins promotes maturation of the 45 S intermediate (white) to a mature 50 S subunit (gray). Along with the complete maturation of the 50 S subunit, GTP at RbgA is hydrolyzed to GDP, and this GDP-bound RbgA and inorganic phosphate leave the mature 50 S subunit, which is now ready to take part in translation. It is also possible that RbgA completes maturation of a late step that does not end in the final maturation of the 50 S subunit.