The Structure of FemXWv in Complex with a Peptidyl‐RNA Conjugate: Mechanism of Aminoacyl Transfer from Ala‐tRNAAla to Peptidoglycan Precursors

To gain insight into the catalytic mechanism of non-ribosomal amino acid transferases, peptidyl-RNA conjugates were synthesized for co-crystallization with FemXWv of Weissella viridescens, which transfers L-Ala from Ala-tRNAAla to the peptidoglycan precursor UDP-MurNAc-pentapeptide. The structure of the resulting complex and mutational studies revealed the mechanism by which FemXWv binds its substrates for substrate-assisted catalysis and stabilization of the tetrahedral intermediate.