An intricate RNA structure with two tRNA-derived motifs directs complex formation between yeast aspartyl-tRNA synthetase and its mRNA.
Accurate translation of genetic information necessitates the tuned expression of a large group of genes. Amongst them, controlled expression of the enzymes catalyzing the aminoacylation of tRNAs, the aminoacyl-tRNA synthetases, is essential to insure translational fidelity. In the yeast Saccharomyces cerevisiae, expression of aspartyl-tRNA synthetase (AspRS) is regulated in a process necessitating recognition of the 5' extremity of AspRS messenger RNA (mRNA(AspRS)) by its translation product and adaptation to the cellular tRNA(Asp) concentration. Here, we have established the folding of the approximately 300 nucleotides long 5' end of mRNA(AspRS) and identified the structural signals involved in the regulation process. We show that the regulatory region in mRNA(AspRS) folds in two independent and symmetrically structured domains spaced by two single-stranded connectors. Domain I displays a tRNA(Asp) anticodon-like stem-loop structure with mimics of the aspartate identity determinants, that is restricted in domain II to a short double-stranded helix. The overall mRNA structure, based on enzymatic and chemical probing, supports a three-dimensional model where each monomer of yeast AspRS binds one individual domain and recognizes the mRNA structure as it recognizes its cognate tRNA(Asp). Sequence comparison of yeast genomes shows that the features within the mRNA recognized by AspRS are conserved in different Saccharomyces species. In the recognition process, the N-terminal extension of each AspRS subunit plays a crucial role in anchoring the tRNA-like motifs of the mRNA on the synthetase.
Ryckelynck
Michaël
M
Département Machineries Traductionnelles, UPR 9002, Institut de Biologie Moléculaire et Cellulaire du CNRS and Université Louis Pasteur, 15, rue René Descartes, F-67084 Strasbourg Cedex, France.
Masquida
Benoit
B
Giegé
Richard
R
Frugier
Magali
M
D001226:Aspartate-tRNA Ligase / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D018983:DNA Footprinting; D017353:Gene Deletion; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000737:chemistry* / Q000378:metabolism*; D012343:RNA, Transfer / Q000737:chemistry* / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics*; D016415:Sequence Alignment; D012689:Sequence Homology, Nucleic Acid; D012995:Solubility
D012333:RNA, Messenger; D012343:RNA, Transfer; D001226:Aspartate-tRNA Ligase