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Literature summary for 2.1.1.182 extracted from
- Control of substrate specificity by a single active site residue of the KsgA methyltransferase (2012), Biochemistry, 51, 466-474.
Cloned(Commentary)
| Cloned (Comment) | Organism |
|---|---|
| expression of wild-type and mutant enzymes in Escherichia coli strain XL1-Blue | Escherichia coli |
Protein Variants
| Protein Variants | Comment | Organism |
|---|---|---|
| C168A | site-directed mutagenesis, the mutation does not affect KsgA activity | Escherichia coli |
| L114P | site-directed mutagenesis of the active site residue, the KsgA mutant shows diminished overall activity, and impaired ability to methylate the N6-methyladenosine intermediate to produce N6,N6-dimethyladenosine. Reduced activity is not due to disruption of 30S substrate binding | Escherichia coli |
| N113A | site-directed mutagenesis of the active site residue, the KsgA mutant shows diminishes activity to a level comparable to L114P without affecting the methylation of N6-methyladenosine. Reduced activity is not due to disruption of 30S substrate binding | Escherichia coli |
Natural Substrates/ Products (Substrates)
| Natural Substrates | Organism | Comment (Nat. Sub.) | Natural Products | Comment (Nat. Pro.) | Rev. | Reac. |
|---|---|---|---|---|---|---|
| 4 S-adenosyl-L-methionine + adenine1518/adenine1519 in 16S rRNA | Escherichia coli | - |
4 S-adenosyl-L-homocysteine + N6-dimethyladenine1518/N6-dimethyladenine1519 in 16S rRNA | - |
? |  |
Organism
| Organism | UniProt | Comment | Textmining |
|---|---|---|---|
| Escherichia coli | - |
- |
- |
Purification (Commentary)
| Purification (Comment) | Organism |
|---|---|
| recombinant wild-type and mutant enzymes from Escherichia coli strain XL1-Blue | Escherichia coli |
Reaction
| Reaction | Comment | Organism | Reaction ID |
|---|---|---|---|
| 4 S-adenosyl-L-methionine + adenine1518/adenine1519 in 16S rRNA = 4 S-adenosyl-L-homocysteine + N6-dimethyladenine1518/N6-dimethyladenine1519 in 16S rRNA | reaction mechanism, overview | Escherichia coli |
Substrates and Products (Substrate)
| Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
|---|---|---|---|---|---|---|
| 4 S-adenosyl-L-methionine + adenine1518/adenine1519 in 16S rRNA | - |
Escherichia coli | 4 S-adenosyl-L-homocysteine + N6-dimethyladenine1518/N6-dimethyladenine1519 in 16S rRNA | - |
? | |
| 4 S-adenosyl-L-methionine + adenine1518/adenine1519 in 16S rRNA | binding of 30S subunit and S-adenosyl-L-methionine, structure, overview. After the S-adenosyl-L-methionine addition, KsgA dissociates rapidly from the subunits. The binding of KsgA to substrate is complex and requires regions of rRNA well beyond helix 45, including regions of the 790 loop | Escherichia coli | 4 S-adenosyl-L-homocysteine + N6-dimethyladenine1518/N6-dimethyladenine1519 in 16S rRNA | - |
? | |
Synonyms
| Synonyms | Comment | Organism |
|---|---|---|
| ksgA methyltransferase | - |
Escherichia coli |
Temperature Optimum [°C]
| Temperature Optimum [°C] | Temperature Optimum Maximum [°C] | Comment | Organism |
|---|---|---|---|
| 30 | - |
assay at | Escherichia coli |
pH Optimum
| pH Optimum Minimum | pH Optimum Maximum | Comment | Organism |
|---|---|---|---|
| 7.4 | - |
assay at | Escherichia coli |
Cofactor
| Cofactor | Comment | Organism | Structure |
|---|---|---|---|
| S-adenosyl-L-methionine | - |
Escherichia coli | |
IC50 Value
| IC50 Value | IC50 Value Maximum | Comment | Organism | Inhibitor | Structure |
|---|---|---|---|---|---|
| additional information | - |
IC50 values of unlabeled wild-type or mutant protein competing with fluorescently labeled wild-type protein for binding to 30S subunits | Escherichia coli | additional information |
General Information
| General Information | Comment | Organism |
|---|---|---|
| evolution | the KsgA family belongs tothe group of S-adenosyl-L-methionine-dependent methyltransferases, known as class I MTases, KsgA is related to DNA adenosine methyltransferases, which transfer only a single methyl group to their target adenosine residue. Part of the discrimination between mono- and dimethyltransferase activity lies in a single residue in the active site, L114; this residue is part of a conserved motif, known as motif IV, which is common to a large group of S-adenosyl-L-methionine-dependent methyltransferases | Escherichia coli |
| physiological function | the KsgA methyltransferase is universally conserved and plays a key role in regulating ribosome biogenesis. KsgA has a complex reaction mechanism, transferring a total of four methyl groups onto two separate adenosine residues, A1518 and A1519, in the small subunit rRNA. This means that the active site pocket must accept both adenosine and N6-methyladenosine as substrates to catalyze formation of the final product N6,N6-dimethyladenosine | Escherichia coli |
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