3vrh
From Proteopedia
Crystal structure of ph0300
Structural highlights
FunctionTTUA_PYRHO Catalyzes the ATP-dependent 2-thiolation of 5-methyluridine residue at position 54 in the T loop of tRNAs, leading to 5-methyl-2-thiouridine (m(5)s(2)U or s(2)T) (PubMed:28655838). This modification allows thermal stabilization of tRNAs in thermophilic microorganisms, and is required for cell growth at high temperatures (By similarity). Can use free sulfide as sulfur source in vitro, which may be also the sulfur source in vivo (PubMed:28655838).[UniProtKB:Q72LF3][1] Publication Abstract from PubMedIn thermophilic bacteria, specific 2-thiolation occurs on the conserved ribothymidine at position 54 (T54) in tRNAs, which is necessary for survival at high temperatures. T54 2-thiolation is achieved by the tRNA thiouridine synthetase TtuA and sulfur-carrier proteins. TtuA has five conserved CXXC/H motifs and the signature PP motif, and belongs to the TtcA family of tRNA 2-thiolation enzymes, for which there is currently no structural information. In this study, we determined the crystal structure of a TtuA homologue from the hyperthermophilic archeaon Pyrococcus horikoshii at 2.1 A resolution. The P. horikoshii TtuA forms a homodimer, and each subunit contains a catalytic domain and unique N- and C-terminal zinc fingers. The catalytic domain has much higher structural similarity to that of another tRNA modification enzyme, TilS (tRNA(Ile) (2) lysidine synthetase), than to the other type of tRNA 2-thiolation enzyme, MnmA. Three conserved cysteine residues are clustered in the putative catalytic site, which is not present in TilS. An in vivo mutational analysis in the bacterium Thermus thermophilus demonstrated that the three conserved cysteine residues and the putative ATP-binding residues in the catalytic domain are important for the TtuA activity. A positively-charged surface that includes the catalytic site and the two zinc fingers is likely to provide the tRNA binding site. Proteins 2013. (c) 2013 Wiley Periodicals, Inc. Crystallographic and mutational studies on the tRNA thiouridine synthetase TtuA.,Nakagawa H, Kuratani M, Goto-Ito S, Ito T, Katsura K, Terada T, Shirouzu M, Sekine SI, Shigi N, Yokoyama S Proteins. 2013 Feb 27. doi: 10.1002/prot.24273. PMID:23444054[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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