Figure 4 : Residue M90 in L22 contributes to the species specificity of MifM stalling.

From: Structure of the Bacillus subtilis 70S ribosome reveals the basis for species-specific stalling

Figure 4

(ac) Conservation between B. subtilis and E. coli of (a) 23S rRNA nucleotides A751 (A798 in B. subtilis) and A1321 (A1360 in B. subtilis) within helices H35 and H50, respectively, as well as the tunnel lumen region of ribosomal proteins (b) L4 and (c) L22. In (b,c) similar and identical residues are shaded grey and black, respectively. (d) Overview of relative positions of MifM to tunnel lumen residues of L4 and L22. (e,f) β-galactosidase activity from the GFP–MifM–LacZ reporter (as in Fig. 3g) expressed in B. subtilis strains bearing wildtype (WT) L22 compared with (e) Ec-tip mutants where B. subtilis residues 80–98 are substituted with the equivalent E. coli residues (see d) and then additionally reverted to B. subtilis residues by substitutions I85F/M86R or K90M, or (f) L22 mutants where all possible amino-acid substitutions at position M90 of B. subtilis L22 were generated. Error bars indicate the s.d. of three independent biological replicates. (g) Interaction between the side chain of M90 of L22 with the base of G748 and potential hydrogen bonding (dashed line) between the backbone of M90 and the phosphate-oxygen of A751.