1qyr
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(New page: 200px<br /><applet load="1qyr" size="450" color="white" frame="true" align="right" spinBox="true" caption="1qyr, resolution 2.10Å" /> '''2.1 Angstrom Crystal...)
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Revision as of 23:00, 20 November 2007
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2.1 Angstrom Crystal structure of KsgA: A Universally Conserved Adenosine Dimethyltransferase
Overview
The bacterial enzyme KsgA catalyzes the transfer of a total of four methyl, groups from S-adenosyl-l-methionine (S-AdoMet) to two adjacent adenosine, bases in 16S rRNA. This enzyme and the resulting modified adenosine bases, appear to be conserved in all species of eubacteria, eukaryotes, and, archaebacteria, and in eukaryotic organelles. Bacterial resistance to the, aminoglycoside antibiotic kasugamycin involves inactivation of KsgA and, resulting loss of the dimethylations, with modest consequences to the, overall fitness of the organism. In contrast, the yeast ortholog, Dim1, is, essential. In yeast, and presumably in other eukaryotes, the enzyme, performs a vital role in pre-rRNA processing in addition to its, methylating activity. Another ortholog has been discovered recently, h-mtTFB in human mitochondria, which has a second function; this enzyme is, a nuclear-encoded mitochondrial transcription factor. The KsgA enzymes are, homologous to another family of RNA methyltransferases, the Erm enzymes, which methylate a single adenosine base in 23S rRNA and confer resistance, to the MLS-B group of antibiotics. Despite their sequence similarity, the, two enzyme families have strikingly different levels of regulation that, remain to be elucidated. We have crystallized KsgA from Escherichia coli, and solved its structure to a resolution of 2.1A. The structure bears a, strong similarity to the crystal structure of ErmC' from Bacillus, stearothermophilus and a lesser similarity to sc-mtTFB, the Saccharomyces, cerevisiae version of h-mtTFB. Comparison of the three crystal structures, and further study of the KsgA protein will provide insight into this, interesting group of enzymes.
About this Structure
1QYR is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.
Reference
Crystal structure of KsgA, a universally conserved rRNA adenine dimethyltransferase in Escherichia coli., O'Farrell HC, Scarsdale JN, Rife JP, J Mol Biol. 2004 May 28;339(2):337-53. PMID:15136037
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