Escherichia coli Ribosomal Protein S1 Unfolds Structured mRNAs Onto the Ribosome for Active Translation Initiation
Figure 3
Domains 1 to 3 of r-protein S1 are essential for the recognition of rpsO mRNA.
(A) Gel retardation assays were performed on complexes formed with the 5′ end-labeled rpsOSD mRNA (psk-rpsOSD) and wild-type r-protein S1 (S1Wt). Lane 1, incubation control of psk-rpsOSD alone; lanes 2–5, complex formation was performed with various concentrations of S1Wt as indicated on the top of the autoradiography. The addition of S1 causes fuzzy bands due to the dissociation of the complex during the migration. (B) Gel retardation assays were done on complexes formed with the 5′ end-labeled mutant C-14G psk-rpsOSD (mut psk-rpsOSD) and S1Wt. Lane 1, incubation control of mut psk-rpsOSD alone; lanes 2–5, complex formation was performed with various concentrations of S1Wt as indicated. (C) Gel retardation assays were done on complexes formed with mut psk-rpsOSD and various truncated forms of r-protein S1. The protein was deleted of either domains 5 and 6 (Δ56), domains 4 to 6 (Δ4–6), domain 1 (Δ1), domains 1 and 2 (Δ12), domains 2 to 6 (Δ2–6), or domains 3 to 6 (Δ3–6). The positions of the complex (RNA-S1) and of the free RNA (RNA) are given. Same legend as in panel B.