Maltose Transport in Escherichia coli K12. A Comparison of Transport Kinetics in Wild-Type and lamba-Resistant Mutants with the Dissociation Constants of the Maltose-Binding Protein as Measured by Fluorescence Quenching

ABSTRACT Changes in the amount of oligopeptide binding protein (OppA) in spontaneous kanamycin-resistant mutants of Escherichia coliwere investigated. Among 20 colonies obtained from 108cells cultured in the presence of 20 μg of kanamycin/ml, 1 colony had no detectable OppA and 7 colonies were mutants with reduced amounts of OppA. Sensitivity of wild-type cells to kanamycin increased slightly by transformation of the oppA gene, but the sensitivity of the mutants increased greatly by the transformation. A mutant with no OppA was found to be a nonsense mutant of the oppA gene at amino acid position 166. In a mutant having a reduced level of OppA, the reduction was due to the decrease in OppA synthesis at the translational level. These mutants were also resistant to other aminoglycoside antibiotics, including streptomycin, neomycin, and isepamicin. Isepamicin uptake activities decreased greatly in these two kinds of mutants. The results support the proposition that aminoglycoside antibiotics are transported into cells by the oligopeptide transport system, and that transport is an important factor for spontaneous resistance to aminoglycoside antibiotics.

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Interspecific reconstitution of maltose transport and chemotaxis in Escherichia coli with maltose-binding protein from various enteric bacteria.

Journal of Bacteriology ◽

10.1128/jb.164.3.1057-1063.1985 ◽

1985 ◽

Vol 164 (3) ◽

pp. 1057-1063 ◽

Cited By ~ 22

Author(s):

M K Dahl ◽

M D Manson

Keyword(s):

Escherichia Coli ◽

Binding Protein ◽

Enteric Bacteria ◽

Maltose Binding Protein ◽

Maltose Transport

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The Periplasmic Cyclodextrin Binding Protein CymE from Klebsiella oxytoca and Its Role in Maltodextrin and Cyclodextrin Transport

Journal of Bacteriology ◽

10.1128/jb.180.10.2630-2635.1998 ◽

1998 ◽

Vol 180 (10) ◽

pp. 2630-2635 ◽

Cited By ~ 34

Author(s):

Markus Pajatsch ◽

Maria Gerhart ◽

Ralf Peist ◽

Reinhold Horlacher ◽

Winfried Boos ◽

...

Keyword(s):

Escherichia Coli ◽

Fluorescence Quenching ◽

Dissociation Constants ◽

Binding Protein ◽

Klebsiella Oxytoca ◽

Uptake System ◽

Gene Products ◽

Periplasmic Binding Protein ◽

E Coli

ABSTRACT Klebsiella oxytoca M5a1 has the capacity to transport and to metabolize α-, β- and γ-cyclodextrins. Cyclodextrin transport is mediated by the products of the cymE,cymF, cymG, cymD, andcymA genes, which are functionally homologous to themalE, 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 α-cyclodextrin, β-cyclodextrin, and γ-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, α-cyclodextrin was taken up by thecym system of K. oxytoca three to five times less efficiently than maltohexaose by the E. coli maltose system. Besides α-cyclodextrin, maltohexaose was also taken up by theK. 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.

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