Deinococcus glutaminyl-tRNA synthetase is a chimer between proteins from an ancient and the modern pathways of aminoacyl-tRNA formation.
Glutaminyl-tRNA synthetase from Deinococcus radiodurans possesses a C-terminal extension of 215 residues appending the anticodon-binding domain. This domain constitutes a paralog of the Yqey protein present in various organisms and part of it is present in the C-terminal end of the GatB subunit of GatCAB, a partner of the indirect pathway of Gln-tRNA(Gln) formation. To analyze the peculiarities of the structure-function relationship of this GlnRS related to the Yqey domain, a structure of the protein was solved from crystals diffracting at 2.3 A and a docking model of the synthetase complexed to tRNA(Gln) constructed. The comparison of the modeled complex with the structure of the E. coli complex reveals that all residues of E. coli GlnRS contacting tRNA(Gln) are conserved in D. radiodurans GlnRS, leaving the functional role of the Yqey domain puzzling. Kinetic investigations and tRNA-binding experiments of full length and Yqey-truncated GlnRSs reveal that the Yqey domain is involved in tRNA(Gln) recognition. They demonstrate that Yqey plays the role of an affinity-enhancer of GlnRS for tRNA(Gln) acting only in cis. However, the presence of Yqey in free state in organisms lacking GlnRS, suggests that this domain may exert additional cellular functions.
Deniziak
Marzanna
M
UPR 9002 Architecture et Reactivité de l'ARN, Université Louis Pasteur, Institut de Biologie Moléculaire et Cellulaire du CNRS, 15, Rue René Descartes, F-67084 Strasbourg Cedex, France.
Sauter
Claude
C
Becker
Hubert Dominique
HD
Paulus
Caroline Alexandra
CA
Giegé
Richard
R
Kern
Daniel
D
D000595:Amino Acid Sequence; D000604:Amino Acyl-tRNA Synthetases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D018360:Crystallography, X-Ray; D034301:Deinococcus / Q000201:enzymology*; D004926:Escherichia coli / Q000201:enzymology; D019143:Evolution, Molecular; D050939:Gene Fusion; D007700:Kinetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019884:Nitrogenous Group Transferases / Q000737:chemistry; D017434:Protein Structure, Tertiary; D012351:RNA, Transfer, Gln / Q000737:chemistry* / Q000378:metabolism; D016415:Sequence Alignment
D001426:Bacterial Proteins; D012351:RNA, Transfer, Gln; D019884:Nitrogenous Group Transferases; C047694:glutamyl-tRNA(Gln) amidotransferase; D000604:Amino Acyl-tRNA Synthetases; C020659:glutaminyl-tRNA synthetase