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J Bacteriol, May 1998, p. 2630-2635, Vol. 180, No. 10
Lehrstuhl für Mikrobiologie der
Universität München,
Received 6 November 1997/Accepted 9 March 1998
Klebsiella oxytoca M5a1 has the capacity to transport
and to metabolize
0021-9193/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
The Periplasmic Cyclodextrin Binding Protein CymE
from Klebsiella oxytoca and Its Role in Maltodextrin and
Cyclodextrin Transport
-,
- and
-cyclodextrins. Cyclodextrin
transport is mediated by the products of the cymE,
cymF, cymG, cymD, and cymA genes, which are functionally homologous to the
malE, malF, malG, malK,
and lamB gene products of Escherichia coli.
CymE, which is the periplasmic binding protein, has been overproduced and purified. By substrate-induced fluorescence quenching, the binding
of ligands was analyzed. CymE bound
-cyclodextrin,
-cyclodextrin, and
-cyclodextrin, with dissociation constants
(Kd) of 0.02, 0.14 and 0.30 µM, respectively,
and linear maltoheptaose, with a Kd of 70 µM.
In transport experiments,
-cyclodextrin was taken up by the
cym system of K. oxytoca three to five times
less efficiently than maltohexaose by the E. coli maltose
system. Besides
-cyclodextrin, maltohexaose was also taken up by the
K. oxytoca cym system, but because of the inability of
maltodextrins to induce the cym system, growth of E. coli mal mutants on linear maltodextrin was not observed when the
cells harbored only the cym uptake system. Strains which gained this capacity by mutation could easily be selected, however.
*
Corresponding author. Mailing address: Institute of
Genetics and Microbiology, Maria-Ward-Straße 1a, D-80638
München, Germany. Phone: 89-17919856. Fax: 89-17919862. E-mail:
august.boeck{at}rz.uni-muenchen.de.
J Bacteriol, May 1998, p. 2630-2635, Vol. 180, No. 10
0021-9193/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
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