Structure-Based Annotation of a Novel Sugar Isomerase from the Pathogenic E. coli O157:H7 |
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Authors: | Laura M van Staalduinen Soo-Jin Yeom Deok-Kun Oh |
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Institution: | 1Department of Biochemistry, Queen's University, Kingston, Ontario, Canada K7L3N6 2Department of Bioscience and Biotechnology, Konkuk University, Seoul 143-701, South Korea |
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Abstract: | Prokaryotes can use a variety of sugars as carbon sources in order to provide a selective survival advantage. The gene z5688 found in the pathogenic Escherichia coli O157:H7 encodes a “hypothetical” protein of unknown function. Sequence analysis identified the gene product as a putative member of the cupin superfamily of proteins, but no other functional information was known. We have determined the crystal structure of the Z5688 protein at 1.6 Å resolution and identified the protein as a novel E. coli sugar isomerase (EcSI) through overall fold analysis and secondary-structure matching. Extensive substrate screening revealed that EcSI is capable of acting on d-lyxose and d-mannose. The complex structure of EcSI with fructose allowed the identification of key active-site residues, and mutagenesis confirmed their importance. The structure of EcSI also suggested a novel mechanism for substrate binding and product release in a cupin sugar isomerase. Supplementation of a nonpathogenic E. coli strain with EcSI enabled cell growth on the rare pentose d-lyxose. |
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Keywords: | EcSI E coli sugar isomerase cPGI cupin phosphoglucose isomerase LI d-lyxose isomerase" target="_blank">d-lyxose isomerase MI d-mannose isomerase" target="_blank">d-mannose isomerase ICP-MS inductively coupled plasma mass spectrometry EDTA ethylenediaminetetraacetic acid |
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