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thrS (Threonine--tRNA ligase)
FEATURES
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FAMILY
DESCRIPTION
Also known as SYT_ECOLI, thrS. Catalyzes the attachment of threonine to tRNA(Thr) in a two-step reaction: L-threonine is first activated by ATP to form Thr-AMP and then transferred to the acceptor end of tRNA(Thr) (PubMed:15079065, PubMed:10881191, PubMed:18997014). The rate-limiting step is amino acid activation in the presence of tRNA (PubMed:18997014). The 2'-OH of the acceptor base (adenine 76, A76) of tRNA(Thr) and His-309 collaborate to transfer L-Thr to the tRNA; substitution of 2'-OH of A76 with hydrogen or fluorine decreases transfer efficiency 760 and 100-fold respectively (PubMed:18997014). The zinc ion in the active site discriminates against charging of the isosteric amino acid valine (PubMed:10881191). Also activates L-serine, but does not detectably transfer it to tRNA(Thr) (PubMed:15079065). Edits incorrectly charged L-seryl-tRNA(Thr) via its editing domain (PubMed:15079065, PubMed:11136973, PubMed:15525511), in a post-transfer reaction probably via water-mediated hydrolysis (PubMed:15525511)., ThrS is also a translational repressor protein, it controls binds its own mRNA in the operator region upstream of the start codon (PubMed:3086882). The mRNA region upstream of the start codon has a tRNA-like secondary structure; mRNA and tRNA compete for binding to ThrRS (PubMed:2254931). ThrRS represses translation by preventing the ribosome from to mRNA, and tRNA(Thr) acts as an antirepressor allowing fine level control of enzyme synthesis (PubMed:2254931). X-ray structures prove that operator mRNA and tRNA bind to overlapping sites in the protein (PubMed:10319817, PubMed:11953757). Homodimer (PubMed:10319817, PubMed:11136973, PubMed:10881191, PubMed:11953757, PubMed:23362938, PubMed:25824639); binds 2 tRNA(Thr) per homodimer, each tRNA contacts both monomers and makes specific contacts with the anticodon and acceptor stems (PubMed:10319817).
Also known as SYT_ECOLI, thrS. Catalyzes the attachment of threonine to tRNA(Thr) in a two-step reaction: L-threonine is first activated by ATP to form Thr-AMP and then transferred to the acceptor end of tRNA(Thr) (PubMed:15079065, PubMed:10881191, PubMed:18997014). The rate-limiting step is amino acid activation in the presence of tRNA (PubMed:189 ...
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thrS

Threonine--tRNA ligase

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4HWS_B
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