The structure of an AspRS-tRNA(Asp) complex reveals a tRNA-dependent control mechanism.
The 2.6 A resolution crystal structure of an inactive complex between yeast tRNA(Asp) and Escherichia coli aspartyl-tRNA synthetase reveals the molecular details of a tRNA-induced mechanism that controls the specificity of the reaction. The dimer is asymmetric, with only one of the two bound tRNAs entering the active site cleft of its subunit. However, the flipping loop, which controls the proper positioning of the amino acid substrate, acts as a lid and prevents the correct positioning of the terminal adenosine. The structure suggests that the acceptor stem regulates the loop movement through sugar phosphate backbone- protein interactions. Solution and cellular studies on mutant tRNAs confirm the crucial role of the tRNA three-dimensional structure versus a specific recognition of bases in the control mechanism.
Moulinier
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L
UPR 9004, Laboratoire de Biologie et Génomique Structurales, Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/ULP, 1 rue Laurent Fries, BP 163, 67404 Illkirch Cedex, France.
Eiler
S
S
Eriani
G
G
Gangloff
J
J
Thierry
J C
JC
Gabriel
K
K
McClain
W H
WH
Moras
D
D
D001226:Aspartate-tRNA Ligase / Q000737:chemistry*; D001483:Base Sequence; D001665:Binding Sites; D002455:Cell Division; D018360:Crystallography, X-Ray; D004926:Escherichia coli / Q000166:cytology / Q000201:enzymology / Q000235:genetics; D017353:Gene Deletion; D006860:Hydrogen Bonding; D046911:Macromolecular Substances; D008958:Models, Molecular; D008969:Molecular Sequence Data; D021122:Protein Subunits; D012349:RNA, Transfer, Asp / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D012441:Saccharomyces cerevisiae / Q000235:genetics; D013045:Species Specificity
D046911:Macromolecular Substances; D021122:Protein Subunits; D012349:RNA, Transfer, Asp; D001226:Aspartate-tRNA Ligase