5.4.99.25: tRNA pseudouridine55 synthase
This is an abbreviated version!
For detailed information about tRNA pseudouridine55 synthase, go to the full flat file.
Word Map on EC 5.4.99.25
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5.4.99.25
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synthases
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pseudouridylation
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anticodon
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rna-guided
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5-fluorouridine
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srnps
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thumb
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snornas
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eukaryal
- 5.4.99.25
- synthases
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pseudouridylation
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anticodon
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rna-guided
- 5-fluorouridine
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srnps
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thumb
- snornas
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eukaryal
Reaction
Synonyms
aCBF5, Cbf5, Mj-Pus10, MjPus10, More, pfuCbf5, pseudouridine 55 synthase, pseudouridine synthase, pseudouridine synthase Pus10, pseudouridine synthase TruB, pseuduridine-55 synthase, PSI synthase, PSI synthase TruB, PSI55 synthase, PSI55 synthaseuB, psi55 tRNA pseudouridine synthase, psi55S, Pus10, Pus4, RNA pseudouridine synthase TruB, TR, tRNA pseudouridine 55 synthase, tRNA pseudouridine synthase, tRNA PSI 55 synthase, tRNA:pseudouridine-55 synthase, tRNA:PSI55 synthase, tRNA:PSI55-synthase, TruB, YNL292w
ECTree
5.4.99.25 tRNA pseudouridine55 synthaseAdvanced search results
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results (Substrates Products
Substrates Products on EC 5.4.99.25 - tRNA pseudouridine55 synthase
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SUBSTRATE 
PRODUCT
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate)
(Substrate)
LITERATURE
(Substrate)
(Substrate)
COMMENTARY
(Product)
(Product)
LITERATURE
(Product)
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
r=reversible
ir=irreversible
?=not specified
tRNA uridine55
tRNA pseudouridine552
substrate: Escherichia coli tRNAPhe
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tRNATrp uridine55
tRNATrp pseudouridine55
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tRNATrp containing or lacking 3'-CCA. aCbf5 and aGar1 together can function as a tRNA Psi55 synthase in a guide RNA-independent manner. This activity is enhanced by aNop10, but not by L7Ae. The aCbf5 alone can also produce Psi55 in tRNAs that contain the canonical 3'-CCA sequence and this activity is stimulated by aGar1. tRNAs lacking 3'-CCA can be modified only by the aCbf5-aGar1 complex. The presence of conserved C (or U) and A at tRNA positions 56 and 58, respectively, is not essential for aCbf5-mediated Psi55 formation
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?
tRNA uridine55
tRNA pseudouridine55
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activity is determined with yeast tRNAPhe (wild-type and mutants). A 17 base oligoribonucleotide analog of the T-arm is equivalent to intact native tRNA as a substrate for pseudouridine 55 synthase. The structures and activities of mutant tRNAs and T-arms are used to analyze substrate recognition by pseudouridine 55 synthase. The 17-mer T-arm is an excellent substrate for the synthase, while disruption of the stem structure of the 17-mer T-arm eliminates activity. Kinetic data on tRNA mutants lacking single T-stem base pairs indicate that only the 53:61 base pair, which maintains the 7 base loop size, is essential for activity. The identities of individual bases in the stem are unimportant provided base pairing is intact. A major function of the T-stem appears to be the maintainence of a stable stem-loop structure and proper presentation of the T-loop to pseudouridine 55 synthase. The 7 base T-loop can be expanded or contracted by 1 base and still retains activity, albeit with a 30fold reduction in kcat. Kinetic analysis of T-loop mutants reveals the requirement for uridine54, uridine55, and adenine58, and a preference for cytosine over uridine at position 56
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tRNA uridine55
tRNA pseudouridine55
substrate: Escherichia coli tRNAPhe
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?
tRNA uridine55
tRNA pseudouridine55
the recombinant protein is specific for uridine55 in tRNA transcripts and reacts neither at other sites for PSI in such transcripts nor with transcripts of 16S or 23S ribosomal RNA or subfragments. Uridine54, uridine32 and uridine39 are not converted to pseudouridine. Stoichiometric formation of psi occurs with no requirement for an external source of energy, indicating that PSI synthesis is thermodynamically favored
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tRNA uridine55
tRNA pseudouridine55
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aCbf5 and aGar1 together can function as a tRNA pseudouridine55 synthase in a guide RNA-independent manner. This activity is enhanced by aNop10, but not by L7Ae. The aCbf5 alone can also produce pseudouridine55 in tRNAs that contain the canonical 3-CCA sequence and this activity is stimulated by aGar1. The presence of C (or U) and A at tRNA position 56 and 58, respectively are not essential for Cbf5-mediated PSI55 formation. Variation in the structure of the anticodon arm of the tRNA does not affect the PSI55 synthase activity
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?
tRNA uridine55
tRNA pseudouridine55
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the bifunctional enzyme can act as synthase for both tRNA pseudouridine54 and pseudouridine55. The two modifications seem to occur independently. Unlike bacterial TruB and yeast Pus4, archaeal Pus10 does not require a U54*A58 reverse Hoogstein base pair and pyrimidine at position 56 to convert tRNA uridine55 to pseudouridine55. Although the T(PSI)PSI-arm of tRNA is a good substrate for both pseudouridine54 and pseudouridine55 synthesis by Mj-Pus10, the production of pseudouridine55 is more efficient than that of pseudouridine54 in this substrate. This contrasts with full-size tRNA substrates, where syntheses of pseudourines appear to be equally efficient
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?
tRNA uridine55
tRNA pseudouridine55
the enzyme also exhibits tRNA pseudouridine54 synthase activity. The forefinger loop (reminiscent of that of RluA) and an Arg and a Tyr residue of archaeal Pus10 as critical determinants for its tRNA pseudouridine54 synthase, but not for its tRNA pseudouridine55 activity. A Leu residue, in addition to the catalytic Asp, is essential for both activities. Archaeal Pus10 proteins must use a different mechanism of recognition for tRNA pseudouridine55 than for the recognition of pseudouridine54. It is proposed that archaeal Pus10 uses two distinct mechanisms for substrate uridine recognition and binding. No mutation mutation is detected that affects only tRNA pseudouridine54 synthase activity, both mechanisms for archaeal Pus10 activities must share some common features
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?
tRNA uridine55
tRNA pseudouridine55
the enzyme also exhibits tRNA pseudouridine54 synthase activity. The forefinger loop (reminiscent of that of RluA) and an Arg and a Tyr residue of archaeal Pus10 as critical determinants for its tRNA pseudouridine54 synthase, but not for its tRNA pseudouridine55 activity. A Leu residue, in addition to the catalytic Asp, is essential for both activities. Archaeal Pus10 proteins must use a different mechanism of recognition for tRNA pseudouridine55 than for the recognition of pseudouridine54. It is proposed that archaeal Pus10 uses two distinct mechanisms for substrate uridine recognition and binding. No mutation mutation is detected that affects only tRNA pseudouridine54 synthase activity, both mechanisms for archaeal Pus10 activities must share some common features
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tRNA uridine55
tRNA pseudouridine55
the stable anchoring of aCBF5 to tRNAs relies on its PUA domain and the tRNA CCA sequence
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tRNA uridine55
tRNA pseudouridine55
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assay with T7-transcribed pfutRNAAsp. Two distinct pseudouridine synthases specifically modify uridine55 in tRNA in vitro: 1. Cbf5, a protein known to play a role in RNA-guided modification of rRNA, and 2. pfuPus10 is not a member of the TruB/Pus4/Cbf5 family of pseudouridine synthases. Pus10 can pseudouridylate a truncated tRNA substrate and a tRNA lacking the 3'CCA. Cbf5 functions only on the full-length tRNA substrate including the 3'CCA end
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?
tRNA uridine55
tRNA pseudouridine55
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uridine55 in Haloferax volcanii tRNATrp. The bifunctional enzyme can act as synthase for both tRNA pseudouridine54 and pseudouridine55. The two modifications seem to occur independently. Unlike bacterial TruB and yeast Pus4, archaeal Pus10 does not require a U54*A58 reverse Hoogstein base pair and pyrimidine at position 56 to convert tRNA U55 to C55
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?
tRNA uridine55
tRNA pseudouridine55
Pus4 catalyses the formation of pseudouridine55 in both mitochondrial and cytoplasmic tRNAs
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tRNA uridine55
tRNA pseudouridine55
the purified Pus4p catalyzes the formation of pseudouridine55 in T7 in vitro transcripts of several yeast tRNA genes. In contrast to the known yeast pseudouridine synthase (Pus1) of broad specificity, no other uridines in tRNA molecules are modified by the cloned recombinant Pus4p
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additional information
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RNA containing 5-fluorouridine is a substrate
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additional information
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RNA containing 5-fluorouridine is a substrate
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additional information
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the enzyme binds much more weakly to small RNA Pab91 than to small RNA Pab21. The Pab91 small ribonucleoprotein particle exhibits a higher catalytic efficiency than the Pab21 small ribonucleoprotein particle. Efficient aCBF5 binding probably relies on the pseudouridylation pocket which is not optimized for high activity in the case of Pab21
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additional information
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efficient formation of 5-fluoro-6-hydroxypseudouridine55 from 5-fluorouridine55 is catalyzed by wild-type enzyme and mutant enzymes Y67F and Y67L
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additional information
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efficient formation of 5-fluoro-6-hydroxypseudouridine55 from 5-fluorouridine55 is catalyzed by wild-type enzyme and mutant enzymes Y67F and Y67L
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