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The sim Operon Facilitates the Transport and Metabolism of Sucrose Isomers in Lactobacillus casei ATCC 334

Thompson, John and Jakubovics, Nicholas and Abraham, Bindu and Hess, Sonja and Pikis, Andreas (2008) The sim Operon Facilitates the Transport and Metabolism of Sucrose Isomers in Lactobacillus casei ATCC 334. Journal of Bacteriology, 190 (9). pp. 3362-3373. ISSN 0021-9193. doi:10.1128/JB.02008-07.

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Inspection of the genome sequence of Lactobacillus casei ATCC 334 revealed two operons that might dissimilate the five isomers of sucrose. To test this hypothesis, cells of L. casei ATCC 334 were grown in a defined medium supplemented with various sugars, including each of the five isomeric disaccharides. Extracts prepared from cells grown on the sucrose isomers contained high levels of two polypeptides with Mrs of ~50,000 and ~17,500. Neither protein was present in cells grown on glucose, maltose or sucrose. Proteomic, enzymatic, and Western blot analyses identified the ~50-kDa protein as an NAD+- and metal ion-dependent phospho-{alpha}-glucosidase. The oligomeric enzyme was purified, and a catalytic mechanism is proposed. The smaller polypeptide represented an EIIA component of the phosphoenolpyruvate-dependent sugar phosphotransferase system. Phospho-{alpha}-glucosidase and EIIA are encoded by genes at the LSEI_0369 (simA) and LSEI_0374 (simF) loci, respectively, in a block of seven genes comprising the sucrose isomer metabolism (sim) operon. Northern blot analyses provided evidence that three mRNA transcripts were up-regulated during logarithmic growth of L. casei ATCC 334 on sucrose isomers. Internal simA and simF gene probes hybridized to ~1.5- and ~1.3-kb transcripts, respectively. A 6.8-kb mRNA transcript was detected by both probes, which was indicative of cotranscription of the entire sim operon.

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Hess, Sonja0000-0002-5904-9816
Additional Information:Copyright © 2008, American Society for Microbiology. Received 26 December 2007/ Accepted 19 February 2008. Published ahead of print on 29 February 2008. We thank Rick Dreyfuss for assistance with photography and computer graphics, Nga Nguyen for microsequence analyses, and Mary Ann Gawinowicz for mass spectrometry fingerprinting. Experiments by Sonja Hess and Bindu Abraham were conducted at the Proteomics and Mass Spectrometry Facility of NIDDK. This work was supported by the Intramural Research Programs of the NIDCR and NIDDK, National Institutes of Health, Bethesda, MD.
Issue or Number:9
Record Number:CaltechAUTHORS:THOjbact08
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ID Code:10333
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Deposited On:30 Apr 2008
Last Modified:08 Nov 2021 21:07

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