A hybrid structural model of the complete Brugia malayi cytoplasmic asparaginyl-tRNA synthetase.
Aminoacyl-tRNA synthetases are validated molecular targets for anti-infective drug discovery because of their essentiality in protein synthesis. Thanks to genome sequencing, it is now possible to systematically study aminoacyl-tRNA synthetases from human eukaryotic parasites as putative targets for novel drug discovery. As part of a program targeting class IIb asparaginyl-tRNA synthetases (AsnRS) from the parasitic nematode Brugia malayi for anti-filarial drugs, we report the complete structure of a eukaryotic AsnRS. Metazoan and fungal AsnRS differ from their bacterial homologues by the addition of a conserved N-terminal extension of about 110 residues whose structure we have determined by solution NMR for the B. malayi enzyme. In addition, we solved by X-ray crystallography a series of structures of the catalytically active N-terminally truncated enzyme (residues 112-548), allowing the structural basis for the mechanism of asparagine activation to be elucidated. The N-terminal domain contains a structured region with a novel fold featuring a lysine-rich helix that is shown by NMR to interact with tRNA. This is connected by an unstructured tether to the remainder of the enzyme, which is highly similar to the known structure of bacterial AsnRS. These data enable a model of the complete AsnRS-tRNA complex to be constructed.
European Molecular Biology Laboratory, Grenoble Outstation, 6 rue Jules Horowitz, 38142 Grenoble Cedex 9, France.
Thibaut
T
Crepin
Francis
F
Peterson
Michael
M
Haertlein
Davin
D
Jensen
Cheng
C
Wang
Stephen
S
Cusack
Michael
M
Kron
D000595:Amino Acid Sequence; D000818:Animals; D001226:Aspartate-tRNA Ligase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D017178:Brugia malayi / Q000201:enzymology* / Q000235:genetics; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D003593:Cytoplasm / Q000201:enzymology; D017931:DNA Primers / Q000235:genetics; D004789:Enzyme Activation; D015801:Helminth Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D017434:Protein Structure, Tertiary; D012346:RNA, Transfer, Amino Acyl / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
D017931:DNA Primers; D015801:Helminth Proteins; D012346:RNA, Transfer, Amino Acyl; D011994:Recombinant Proteins; D001226:Aspartate-tRNA Ligase; C029194:asparaginyl-tRNA synthetase