2iy5: Difference between revisions
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==Overview== | ==Overview== | ||
The crystal structure of the ternary complex of (alphabeta)(2), heterotetrameric phenylalanyl-tRNA synthetase (PheRS) from Thermus, thermophilus with cognate tRNA(Phe) and a nonhydrolyzable, phenylalanyl-adenylate analogue (PheOH-AMP) has been determined at 3.1 A, resolution. It reveals conformational changes in tRNA(Phe) induced by the, PheOH-AMP binding. The single-stranded 3' end exhibits a hairpin, conformation in contrast to the partial unwinding observed previously in, the binary PheRS.tRNA(Phe) complex. The CCA end orientation is stabilized, by extensive base-specific interactions of A76 and C75 with the protein, and by intra-RNA interactions of A73 with adjacent nucleotides. The, 4-amino group of the "bulged out" C75 is trapped by two negatively charged, residues of the beta .. | The crystal structure of the ternary complex of (alphabeta)(2), heterotetrameric phenylalanyl-tRNA synthetase (PheRS) from Thermus, thermophilus with cognate tRNA(Phe) and a nonhydrolyzable, phenylalanyl-adenylate analogue (PheOH-AMP) has been determined at 3.1 A, resolution. It reveals conformational changes in tRNA(Phe) induced by the, PheOH-AMP binding. The single-stranded 3' end exhibits a hairpin, conformation in contrast to the partial unwinding observed previously in, the binary PheRS.tRNA(Phe) complex. The CCA end orientation is stabilized, by extensive base-specific interactions of A76 and C75 with the protein, and by intra-RNA interactions of A73 with adjacent nucleotides. The, 4-amino group of the "bulged out" C75 is trapped by two negatively charged, residues of the beta subunit (Glubeta31 and Aspbeta33), highly conserved, in eubacterial PheRSs. The position of the A76 base is stabilized by, interactions with Hisalpha212 of motif 2 (universally conserved in PheRSs), and class II-invariant Argalpha321 of motif 3. Important conformational, changes induced by the binding of tRNA(Phe) and PheOH-AMP are observed in, the catalytic domain: the motif 2 loop and a "helical" loop (residues, 139-152 of the alpha subunit) undergo coordinated displacement;, Metalpha148 of the helical loop adopts a conformation preventing the 2'-OH, group of A76 from approaching the alpha-carbonyl carbon of PheOH-AMP. The, unfavorable position of the terminal ribose stems from the absence of the, alpha-carbonyl oxygen in the analogue. Our data suggest that the, idiosyncratic feature of PheRS, which aminoacylates the 2'-OH group of the, terminal ribose, is dictated by the system-specific topology of the CCA, end-binding site. | ||
==About this Structure== | ==About this Structure== | ||
2IY5 is a | 2IY5 is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Thermus_thermophilus Thermus thermophilus] with MG and FYA as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Phenylalanine--tRNA_ligase Phenylalanine--tRNA ligase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=6.1.1.20 6.1.1.20] Structure known Active Site: AC1. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=2IY5 OCA]. | ||
==Reference== | ==Reference== | ||
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[[Category: trna-binding]] | [[Category: trna-binding]] | ||
''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on | ''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Mon Nov 5 14:15:19 2007'' | ||
