Sandbox Reserved 704: Difference between revisions
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Most aaRSs interact with the tRNA anticodon loop in order to form aminoacyl-tRNA complex. But in the case of archaeal LeuRSs, none of them use this recognition mode. In fact, LeuRSs use two identity elements: the discriminator A73 and the long variable arm. | Most aaRSs interact with the tRNA anticodon loop in order to form aminoacyl-tRNA complex. But in the case of archaeal LeuRSs, none of them use this recognition mode. In fact, LeuRSs use two identity elements: the discriminator A73 and the long variable arm. | ||
==== | ==== Recognition of the long variable arm ==== | ||
The first identity element in the complex is the recognition between the long variable arm of tRNA Leu and C-terminal residues of LeuRS. These residues recognize nucleotides localized at the tip of the arm but not at the stem region of the arm. This characteristic avoids interactions of tRNA Leu with SerRS and TyrRS, which also recognize tRNA with a long variable arm. It is not a direct interaction but a pocket is formed for a tip of the variable arm. | The first identity element in the complex is the recognition between the long variable arm of tRNA Leu and C-terminal residues of LeuRS. These residues recognize nucleotides localized at the tip of the arm but not at the stem region of the arm. This characteristic avoids interactions of tRNA Leu with SerRS and TyrRS, which also recognize tRNA with a long variable arm. It is not a direct interaction but a pocket is formed for a tip of the variable arm. | ||
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==== | ==== Interactions with the discriminator, A73 ==== | ||
LeuRS employs the discriminator A73 as second identity element. A73 is localized in the tRNA 3’ region which has two conformations: the canonical ‘aminoacylation state’ and the ‘intermediate state’. Consequently, there is two recognition modes of A73, depending on complex structure. | LeuRS employs the discriminator A73 as second identity element. A73 is localized in the tRNA 3’ region which has two conformations: the canonical ‘aminoacylation state’ and the ‘intermediate state’. Consequently, there is two recognition modes of A73, depending on complex structure. | ||
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The translocation between these two states seems to be allowed thanks to the flexibility of the CCA end. It is able to go towards either the aminoacylation site either the editing site whereas the rest of the tRNA remains bound to the enzyme core. These two conformation states involved two modes of A73 recognition and also of C74, C75 and A73, residues of the 3’-terminal region. | The translocation between these two states seems to be allowed thanks to the flexibility of the CCA end. It is able to go towards either the aminoacylation site either the editing site whereas the rest of the tRNA remains bound to the enzyme core. These two conformation states involved two modes of A73 recognition and also of C74, C75 and A73, residues of the 3’-terminal region. | ||
== References == | == References == | ||
<references/> | <references/> | ||
