FIG 3.

(A) EttA (blue) bound to the 50S ribosomal subunit in complex with P-tRNA^fMet (red) (RCSB Protein Database [PDB] accession numbers 3J5S [19] and 3I9C [24] and binding sites of clindamycin (green) (PDB accession number 3OFZ [25]) and SgA and dalfopristin (purple) (PDB accession number 1SM1 [21]). The arm subdomain of EttA (bright blue) and the PtlM domain (dark blue) are indicated. The enlargement shows a detailed view of the PtlM domain interacting with the stem of P-tRNA^fMet in the direction toward bound antibiotics. (B) Significant Pfam-A matches of the Vga(A) linker with ABC_tran_2 domain and sequence alignment with the PtlM domain of EttA. The hidden Markov model sequence (HMM), match between HMM and Vga(A) (MATCH), and posterior probability (PP) (the degree of confidence in each individual aligned residue) are given. Amino acid residues of Vga(A) and EttA that are identical (red) and the antibiotic specificity site of Vga(A) (green) are indicated. The bright blue lines represent the regions of contact of PtlM with P-site tRNA, and the gray lines represent regions of contact of PtlM with 23S rRNA (19).