FIG 6.
YhhY is an acetyltransferase that detoxifies nonhydrolyzable aminoacyl adenylates in vivo and in vitro. (A) A multiple sequence alignment of E. coli Rim proteins, MccECTD, SpeG, and the YhhY protein. The extent of sequence conservation is indicated by background shading. Catalytic and substrate binding residues are marked with asterisks. Residues 22, 41, and 54 of RimL correspond to known adenine-binding residues of MccECTD and likely adenine-binding residues of YhhY: RimL Lys22 corresponds to His21 of YhhY; Trp41 corresponds to Trp453 of MccE (Trp46 of MccECTD) and Trp41 of YhhY, and Thr54 corresponds to Phe466 of MccE (Phe59 of MccECTD) (17). Residue Cys134 of RimL forms a disulfide bond with acetyl-CoA; Ser141 and Glu160 act as general acid/base catalysts of the acetyltransferase reaction. Alignment was built using MUSCLE software, and the figure was prepared using GENEDOC. (B) LSA was incubated with extracts prepared from indicated cells and subjected to MALDI-MS analysis. Only relevant portions of mass spectra are shown.