pubmed-article:12767240 | rdf:type | pubmed:Citation | lld:pubmed |
pubmed-article:12767240 | lifeskim:mentions | umls-concept:C0085495 | lld:lifeskim |
pubmed-article:12767240 | lifeskim:mentions | umls-concept:C0008633 | lld:lifeskim |
pubmed-article:12767240 | lifeskim:mentions | umls-concept:C1711351 | lld:lifeskim |
pubmed-article:12767240 | lifeskim:mentions | umls-concept:C0332120 | lld:lifeskim |
pubmed-article:12767240 | lifeskim:mentions | umls-concept:C0441712 | lld:lifeskim |
pubmed-article:12767240 | lifeskim:mentions | umls-concept:C0051637 | lld:lifeskim |
pubmed-article:12767240 | lifeskim:mentions | umls-concept:C0596448 | lld:lifeskim |
pubmed-article:12767240 | pubmed:issue | 21 | lld:pubmed |
pubmed-article:12767240 | pubmed:dateCreated | 2003-5-27 | lld:pubmed |
pubmed-article:12767240 | pubmed:abstractText | The aminoglycoside 6'-N-acetyltransferase AAC(6')-Ii from Enterococcus faecium is an important microbial resistance determinant and a member of the GCN5-related N-acetyltransferase (GNAT) superfamily. We report here the further characterization of this enzyme in terms of the kinetic mechanism of acetyl transfer and identification of rate-contributing step(s) in catalysis, as well as investigations into the binding of both acetyl-CoA and aminoglycoside substrates to the AAC(6')-Ii dimer. Product and dead-end inhibition studies revealed that AAC(6')-Ii follows an ordered bi-bi ternary complex mechanism with acetyl-CoA binding first followed by antibiotic. Solvent viscosity studies demonstrated that aminoglycoside binding and product release govern the rate of acetyl transfer, as evidenced by changes in both the k(cat)/K(b) for aminoglycoside and k(cat), respectively, with increasing solvent viscosity. Solvent isotope effects were consistent with our viscosity studies that diffusion-controlled processes and not the chemical step were rate-limiting in drug modification. The patterns of partial and mixed inhibition observed during our mechanistic studies were followed up by investigating the possibility of subunit cooperativity in the AAC(6')-Ii dimer. Through the use of AAC-Trp(164) --> Ala, an active mutant which exists as a monomer in solution, the partial nature of the competitive inhibition observed in wild-type dead-end inhibition studies was alleviated. Isothermal titration calorimetry studies also indicated two nonequivalent antibiotic binding sites for the AAC(6')-Ii dimer but only one binding site for the Trp(164) --> Ala mutant. Taken together, these results demonstrate subunit cooperativity in the AAC(6')-Ii dimer, with possible relevance to other oligomeric members of the GNAT superfamily. | lld:pubmed |
pubmed-article:12767240 | pubmed:language | eng | lld:pubmed |
pubmed-article:12767240 | pubmed:journal | http://linkedlifedata.com/r... | lld:pubmed |
pubmed-article:12767240 | pubmed:citationSubset | IM | lld:pubmed |
pubmed-article:12767240 | pubmed:chemical | http://linkedlifedata.com/r... | lld:pubmed |
pubmed-article:12767240 | pubmed:chemical | http://linkedlifedata.com/r... | lld:pubmed |
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pubmed-article:12767240 | pubmed:chemical | http://linkedlifedata.com/r... | lld:pubmed |
pubmed-article:12767240 | pubmed:status | MEDLINE | lld:pubmed |
pubmed-article:12767240 | pubmed:month | Jun | lld:pubmed |
pubmed-article:12767240 | pubmed:issn | 0006-2960 | lld:pubmed |
pubmed-article:12767240 | pubmed:author | pubmed-author:WrightGerard... | lld:pubmed |
pubmed-article:12767240 | pubmed:author | pubmed-author:NorthropDexte... | lld:pubmed |
pubmed-article:12767240 | pubmed:author | pubmed-author:DrakerKari-an... | lld:pubmed |
pubmed-article:12767240 | pubmed:issnType | Print | lld:pubmed |
pubmed-article:12767240 | pubmed:day | 3 | lld:pubmed |
pubmed-article:12767240 | pubmed:volume | 42 | lld:pubmed |
pubmed-article:12767240 | pubmed:owner | NLM | lld:pubmed |
pubmed-article:12767240 | pubmed:authorsComplete | Y | lld:pubmed |
pubmed-article:12767240 | pubmed:pagination | 6565-74 | lld:pubmed |
pubmed-article:12767240 | pubmed:dateRevised | 2006-11-15 | lld:pubmed |
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pubmed-article:12767240 | pubmed:meshHeading | pubmed-meshheading:12767240... | lld:pubmed |
pubmed-article:12767240 | pubmed:year | 2003 | lld:pubmed |
pubmed-article:12767240 | pubmed:articleTitle | Kinetic mechanism of the GCN5-related chromosomal aminoglycoside acetyltransferase AAC(6')-Ii from Enterococcus faecium: evidence of dimer subunit cooperativity. | lld:pubmed |
pubmed-article:12767240 | pubmed:affiliation | Antimicrobial Research Centre, Department of Biochemistry, McMaster University, 1200 Main Street West, Ontario L8N 3Z5, Canada. | lld:pubmed |
pubmed-article:12767240 | pubmed:publicationType | Journal Article | lld:pubmed |
pubmed-article:12767240 | pubmed:publicationType | Research Support, Non-U.S. Gov't | lld:pubmed |
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