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Literature summary extracted from

  • Arhin, G.; Ullu, E.; Tschudi, C.
    2'-O-Methylation of position 2 of the trypanosome spliced leader cap 4 is mediated by a 48 kDa protein related to vaccinia virus VP39 (2006), Mol. Biochem. Parasitol., 147, 137-139.
    View publication on PubMed

Cloned(Commentary)

EC Number Cloned (Comment) Organism
2.1.1.296 primer extension analysis, functional expression observed of the MT48 gene tagged at the C-terminus with an HA epitope in mt48-/- cells Trypanosoma brucei

Protein Variants

EC Number Protein Variants Comment Organism
2.1.1.296 additional information silencing of TbMT48 mRNA by RNAi downregulation does not produce a lethal phenotype, as MT48-RNAi trypanosomes remain viable even after 10 days of tetracycline induction, generation of MT48 KO clonal cell lines by homologous recombination with PCR-generated cassettes. An observed defect in cap 4 modification, specific for MT48 ablation, can be complemented by reintroduction of a copy of the MT48 gene into mt48-/- cells Trypanosoma brucei

Molecular Weight [Da]

EC Number Molecular Weight [Da] Molecular Weight Maximum [Da] Comment Organism
2.1.1.296 48000
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x * 48000, SDS-PAGE Trypanosoma brucei

Natural Substrates/ Products (Substrates)

EC Number Natural Substrates Organism Comment (Nat. Sub.) Natural Products Comment (Nat. Pro.) Rev. Reac.
2.1.1.296 additional information Trypanosoma brucei a conventional 5'-terminal structure of eukaryotic mRNAs consists of a 7-methylguanosine (m7G) moiety linked to the first transcribed nucleotide by a 5' to 5' triphosphate bridge resulting in the structure m7GpppN, which is referred to as cap 0, and most often the first and second transcribed nucleotide carry 2'-O-methyl groups (cap 1 and cap 2 structures, respectively). The cap2 methyltransferase, EC 2.1.1.296 transfers the methyl group to the second nucleotide. In contrast, four nucleotides adjacent to the m7G cap are methylated at the SL RNA 5' end to generate a cap 4 structure: m7G-ppp-N6,N6,2'-O-trimethyladenosine-p-2'-O-methyladenosine-p-2'-O-methylcytosine-p-N3,2'-O-methyluridine. The cap 4 structure seems to be restricted to the family Trypanosomatidae ?
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?

Organism

EC Number Organism UniProt Comment Textmining
2.1.1.296 Trypanosoma brucei Q385S9
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Substrates and Products (Substrate)

EC Number Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
2.1.1.296 additional information a conventional 5'-terminal structure of eukaryotic mRNAs consists of a 7-methylguanosine (m7G) moiety linked to the first transcribed nucleotide by a 5' to 5' triphosphate bridge resulting in the structure m7GpppN, which is referred to as cap 0, and most often the first and second transcribed nucleotide carry 2'-O-methyl groups (cap 1 and cap 2 structures, respectively). The cap2 methyltransferase, EC 2.1.1.296 transfers the methyl group to the second nucleotide. In contrast, four nucleotides adjacent to the m7G cap are methylated at the SL RNA 5' end to generate a cap 4 structure: m7G-ppp-N6,N6,2'-O-trimethyladenosine-p-2'-O-methyladenosine-p-2'-O-methylcytosine-p-N3,2'-O-methyluridine. The cap 4 structure seems to be restricted to the family Trypanosomatidae Trypanosoma brucei ?
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?
2.1.1.296 additional information the enzyme builds the cap 4 structure, usage of an assay with digestion with ribonuclease T2, to monitor the presence of 2'-O-modifications at positions +1 to +4 of the SL sequence Trypanosoma brucei ?
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?
2.1.1.296 S-adenosyl-L-methionine + a 5'-(N7-methyl 5'-triphosphoguanosine)-(2'-O-methyl-purine-ribonucleotide)-(ribonucleotide)-[mRNA]
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Trypanosoma brucei S-adenosyl-L-homocysteine + a 5'-(N7-methyl 5'-triphosphoguanosine)-(2'-O-methyl-purine-ribonucleotide)-(2'-O-methyl-ribonucleotide)-[mRNA]
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?

Subunits

EC Number Subunits Comment Organism
2.1.1.296 ? x * 48000, SDS-PAGE Trypanosoma brucei

Synonyms

EC Number Synonyms Comment Organism
2.1.1.296 MT48
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Trypanosoma brucei
2.1.1.296 TbMT48
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Trypanosoma brucei

Cofactor

EC Number Cofactor Comment Organism Structure
2.1.1.296 S-adenosyl-L-methionine binding domain structure, overview Trypanosoma brucei

General Information

EC Number General Information Comment Organism
2.1.1.296 evolution the enzyme shows significant sequence and structural similarities to vaccinia virus VP39, another cap-specific RNA 2'-O-methyltransferase. TbMT48 or TbMT57 are two protein components of the cap 4 biosynthetic machinery Trypanosoma brucei
2.1.1.296 malfunction an observed defect in cap 4 modification is a specific effect of MT48 ablation Trypanosoma brucei
2.1.1.296 additional information enzyme MT48 structural modeling using the VP39 crystal structure as a template, TbMT48 domains involved in S-adenosyl-methionine and cap binding, overview Trypanosoma brucei
2.1.1.296 physiological function TbMT48 or TbMT57 are two protein components of the cap 4 biosynthetic machinery. The enzymes involved in cap 4 biogenesis, TbMT48 and TbMT57, are encoded by non-essential genes, considering that the SL cap 4 structure is a crucial determinant for trans-splicing competence of the SL RNA Trypanosoma brucei