A eubacterial Mycobacterium tuberculosis tRNA synthetase is eukaryote-like and resistant to a eubacterial-specific antisynthetase drug.
We report here the cloning and primary structure of Mycobacterium tuberculosis isoleucyl-tRNA synthetase. The predicted 1035-amino acid protein is significantly more similar in sequence to eukaryote cytoplasmic than to other eubacterial isoleucyl-tRNA synthetases. This similarity correlates with the enzyme being resistant to pseudomonic acid A, a potent inhibitor of Escherichia coli and other eubacterial isoleucyl-tRNA synthetases, but not of eukaryote cytoplasmic enzymes. Consistent with its eukaryote-like features, and unlike E. coli isoleucyl-tRNA synthetase, the M. tuberculosis enzyme charged yeast isoleucine tRNA. In spite of these eukaryote-like features, M. tuberculosis isoleucyl-tRNA synthetase exhibited highly specific cross-species aminoacylation, as demonstrated by its ability to complement isoleucyl-tRNA synthetase-deficient mutants of E. coli. When introduced into a pseudomonic acid-sensitive wild-type strain of E. coli, the M. tuberculosis enzyme conferred trans-dominant resistance to the drug. The results demonstrate that the sequence of a tRNA synthetase could have predictive value with respect to the interaction of that synthetase with a specific inhibitor. The results also demonstrate that mobilization of a pathogen's gene for a drug-resistant protein target can spread resistance to other, normally drug-sensitive pathogens infecting the same host.
Sassanfar
M
M
Cubist Pharmaceuticals, Cambridge, Massachusetts 02139, USA.
Kranz
J E
JE
Gallant
P
P
Schimmel
P
P
Shiba
K
K
D000595:Amino Acid Sequence; D001105:Archaea / Q000201:enzymology* / Q000235:genetics; D001483:Base Sequence; D003001:Cloning, Molecular; D017931:DNA Primers; D004926:Escherichia coli; D005051:Eubacterium / Q000201:enzymology / Q000235:genetics; D007533:Isoleucine-tRNA Ligase / Q000096:biosynthesis / Q000737:chemistry* / Q000378:metabolism*; D007700:Kinetics; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009169:Mycobacterium tuberculosis / Q000201:enzymology* / Q000235:genetics; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D017510:Protein Folding; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
D017931:DNA Primers; D011994:Recombinant Proteins; D007533:Isoleucine-tRNA Ligase