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Literature summary for 5.4.99.25 extracted from

  • Gu, X.; Yu, M.; Ivanetich, K.M.; Santi, D.V.
    Molecular recognition of tRNA by tRNA pseudouridine 55 synthase (1998), Biochemistry, 37, 339-343.
    View publication on PubMed

KM Value [mM]

KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
additional information
-
additional information Km-values are determined for wild-type and mutant forms of yeast tRNAPhe Escherichia coli
0.78
-
tRNA uridine55 in yeast tRNAPhe, pH 8.0, 37°C Escherichia coli

Organism

Organism UniProt Comment Textmining
Escherichia coli
-
-
-

Substrates and Products (Substrate)

Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
tRNA uridine55 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 Escherichia coli tRNA pseudouridine55
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Synonyms

Synonyms Comment Organism
tRNA pseudouridine 55 synthase
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Escherichia coli

Temperature Optimum [°C]

Temperature Optimum [°C] Temperature Optimum Maximum [°C] Comment Organism
37
-
assay at Escherichia coli

Turnover Number [1/s]

Turnover Number Minimum [1/s] Turnover Number Maximum [1/s] Substrate Comment Organism Structure
additional information
-
additional information turnover numbers are determined for wild-type and mutant forms of yeast tRNAPhe. The 7 base T-loop can be expanded or contracted by 1 base and still retains activity, albeit with a 30fold reduction in kcat Escherichia coli
0.24
-
tRNA uridine55 in yeast tRNAPhe, pH 8.0, 37°C Escherichia coli

pH Optimum

pH Optimum Minimum pH Optimum Maximum Comment Organism
8
-
assay at Escherichia coli