Structure of Mycobacterium tuberculosis Phe-tRNA synthetase reveals ligand binding and two-stage tRNA recognition

Abstract Tuberculosis, caused by Mycobacterium tuberculosis , responsible for ~1.5 million fatalities in 2018, is the deadliest infectious disease. Global spread of multidrug resistant TB is a public health threat. Aminoacyl-tRNA synthetases are plausible candidates as potential targets because they play pivotal roles in translating the DNA code into protein sequence by attaching specific amino acid to their cognate tRNAs. One of the best characterized synthetases is specific for L-Phe and tRNA Phe . Here we report structures of M. tuberculosis Phe-tRNA synthetase complexed with precursor tRNA and either phenylalanine or a phenylalanine adenylate analog, 5′-O-(N-phenylalanyl)sulfamoyl-adenosine. Crystallographic models for the first time reveal two modes of interaction with tRNA: an initial recognition via the anticodon loop and stem only and productive binding with interaction of the 3’ end of tRNA Phe with the adenylate site. We biochemically characterize the enzyme and provide the highest resolution, most complete view of the Phe-tRNA synthetase/tRNA Phe system to date.