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J. Biol. Chem., Vol. 281, Issue 26, 17900-17908, June 30, 2006
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-D-glucopyranoside and the Five
-D-Glucosyl-D-fructose Isomers of Sucrose*
1
2
From the
Microbial Biochemistry and Genetics Unit, Oral Infection and Immunity Branch, NIDCR, and the
Proteomics and Mass Spectrometry Facility, NIDDK, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland 20892 and the ¶Departement für Chemie und Biochemie, Universität Bern, CH-3012 Bern, Switzerland
Strains of Escherichia coli K12, including MG-1655, accumulate methyl-
-D-glucopyranoside via the phosphoenolpyruvate-dependent glucose:phosphotransferase system (IICBGlc/IIAGlc). High concentrations of intracellular methyl-
-D-glucopyranoside 6-phosphate are toxic, and cell growth is prevented. However, transformation of E. coli MG-1655 with a plasmid (pAP1) encoding the gene aglB from Klebsiella pneumoniae resulted in excellent growth of the transformant MG-1655 (pAP1) on the glucose analog. AglB is an unusual NAD+/Mn2+-dependent phospho-
-glucosidase that promotes growth of MG-1655 (pAP1) by catalyzing the in vivo hydrolysis of methyl-
-D-glucopyranoside 6-phosphate to yield glucose 6-phosphate and methanol. When transformed with plasmid pAP2 encoding the K. pneumoniae genes aglB and aglA (an
-glucoside-specific transporter AglA (IICBAgl)), strain MG-1655 (pAP2) metabolized a variety of other
-linked glucosides, including maltitol, isomaltose, and the following five isomers of sucrose: trehalulose
(1
1), turanose
(1
3), maltulose
(1
4), leucrose
(1
5), and palatinose
(1
6). Remarkably, MG-1655 (pAP2) failed to metabolize sucrose
(1
2). The E. coli K12 strain ZSC112L (ptsG::cat manXYZ nagE glk lac) can neither grow on glucose nor transport methyl-
-D-glucopyranoside. However, when transformed with pTSGH11 (encoding ptsG) or pAP2, this organism provided membranes that contained either the PtsG or AglA transporters, respectively. In vitro complementation of transporter-specific membranes with purified general phosphotransferase components showed that although PtsG and AglA recognized glucose and methyl-
-D-glucopyranoside, only AglA accepted other
-D-glucosides as substrates. Complementation experiments also revealed that IIAGlc was required for functional activity of both PtsG and AglA transporters. We conclude that AglA, AglB, and IIAGlc are necessary and sufficient for growth of E. coli K12 on methyl-
-D-glucoside and related
-D-glucopyranosides.
Received for publication, February 7, 2006 , and in revised form, March 27, 2006.
* This work was supported by the NIDCR and NIDDK Intramural Research Programs, National Institutes of Health. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
1 Present address: Center for Drug Evaluation and Research, Food and Drug Administration, Silver Spring, MD 20993.
2 To whom correspondence should be addressed: NIDCR, National Institutes of Health, Bldg. 30, Rm. 325, Convent Dr. MSC-4350, Bethesda, MD 20892. Tel.: 301-496-4083; Fax: 301-402-1064; E-mail: jthompson{at}dir.nidcr.nih.gov.
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