Overview for MACiE Entry M0056
EC Number: 220.127.116.11 (A member of the Isomerases, Intramolecular transferases, Transferring other groups)
Enzyme Name: tRNA-pseudouridine synthase I
Biological Species: Thermotoga maritima (Bacteria)
Catalytic Chain UniprotKB Accession Codes:
- Q9WZW0 - tRNA pseudouridine synthase B
Representative PDB Code: 1ze1 - CONFORMATIONAL CHANGE OF PSEUDOURIDINE 55 SYNTHASE UPON ITSASSOCIATION WITH RNA SUBSTRATE (Resolution = 2.90 Å).
Catalytic CATH Codes:
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Overall Comment: There are two commonly proposed mechanisms for this enzyme. Based on references 2 and 3 we show the acyl-enzyme mechanism rather than the alternative Michael addition mechanism.
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Stepwise Description of the Reaction
|Step 1||Asp39 initiates a nucleophilic attack upon the C1 of the uridine tRNA in a substitution reaction, displacing the uridine base as an anion.|
|Step 2||The uridine undergoes rotation within the active site. The anion then initiates double bond rearrangement, which results in nucleophilic attack of the transient carbanion (from the C=C) on the covalently bound tRNA molecule in a substitution reaction, displacing Asp39.|
|Step 3||The pseudouridine then deprotonates Tyr67, which in turn deprotonates the sugar bound carbon of the ring forming the final product.|
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Catalytic Residues Involved
||Location of Function
- P. G. Foster et al. (2000), Nat. Struct. Biol., 7, 23-27. The structural basis for tRNA recognition and pseudouridine formation by pseudouridine synthase I.
- E. G. Mueller (2002), Nat. Struct. Biol., 9, 320-322. Chips off the old block.
- K. Phannachet et al. (2005), Biochemistry, 44, 15488-15494. Dissecting the roles of a strictly conserved tyrosine in substrate recognition and catalysis by pseudouridine 55 synthase.
Homologue information for M0056 (1ze1)
MACiE Homologues (within the PDB)
MACiE Homologues (within UniprotKB/SwissProt)
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