1o9g
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(New page: 200px<br /><applet load="1o9g" size="450" color="white" frame="true" align="right" spinBox="true" caption="1o9g, resolution 1.50Å" /> '''RRNA METHYLTRANSFERA...)
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Revision as of 22:27, 24 November 2007
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RRNA METHYLTRANSFERASE AVIRA FROM STREPTOMYCES VIRIDOCHROMOGENES AT 1.5A
Overview
The emergence of antibiotic-resistant bacterial strains is a widespread, problem in contemporary medical practice and drug design. It is therefore, important to elucidate the underlying mechanism in each case. The, methyltransferase AviRa from Streptomyces viridochromogenes mediates, resistance to the antibiotic avilamycin, which is closely related to, evernimicin, an oligosaccharide antibiotic that has been used in medical, studies. The structure of AviRa was determined by X-ray diffraction at, 1.5A resolution. Phases were obtained from one selenomethionine residue, introduced by site-directed mutagenesis. The chain-fold is similar to that, of most methyltransferases, although AviRa contains two additional helices, as a specific feature. A putative-binding site for the cofactor, S-adenosyl-L-methionine was derived from homologous structures. It agrees, with the conserved pattern of interacting amino acid residues. AviRa, methylates a specific guanine base within the peptidyltransferase loop of, the 23S ribosomal RNA. Guided by the target, the enzyme was docked to the, cognate ribosomal surface, where it fit well into a deep cleft without, contacting any ribosomal protein. The two additional alpha-helices of, AviRa filled a depression in the surface. Since the transferred methyl, group of the cofactor is in a pocket beneath the enzyme surface, the, targeted guanine base has to flip out for methylation.
About this Structure
1O9G is a Single protein structure of sequence from Streptomyces viridochromogenes. Full crystallographic information is available from OCA.
Reference
Crystal structure of the avilamycin resistance-conferring methyltransferase AviRa from Streptomyces viridochromogenes., Mosbacher TG, Bechthold A, Schulz GE, J Mol Biol. 2003 May 23;329(1):147-57. PMID:12742024
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