The influence of maltoporin affinity on the transport of maltose and maltohexaose into Escherichia coli

Ferenci, Thomas; Lee, Kin-Sang

doi:10.1016/0005-2736(87)90193-3

Cited by 8 publications

(8 citation statements)

References 13 publications

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“…4). The more strongly affected variants were, in addition to the Arg8--His variant described earlier (13), the insertion at 9 to 10 and the two strains with mutations near residue 360. The insertion at residue 119 to 120 exhibited a pore totally blocked towards lactose, suggesting a greatly decreased nonspecific pore size in this variant.…”

Section: Resultsmentioning

confidence: 78%

“…The influence of the substitutions and insertions on the pore properties of maltoporin were investigated by using lactose as a substrate, as previously described (13). Lactose is a nonmaltosaccharide which can be used to probe the nonselective pore in maltoporin.…”

Section: Resultsmentioning

confidence: 99%

“…A maltodextrin-binding site has indeed been demonstrated (14), and its affinity correlates well with transport affinities measured in vivo and in vitro (3,13,19). The unique feature of this binding site among transport proteins is that it is readily amenable to genetic analysis, and several residues that influence binding and transport have been recently identified (18; A. Charbit, K. Gehring, H. Nikaido, T. Ferenci, and M. Hofnung, J. Mol.…”

mentioning

confidence: 79%

“…The kinetics of maltose transport and its inhibition by maltohexaose were assayed in bacteria with chromosomal mutant lamB alleles but lacking other major porins (13). The non-maltodextrin-specific pore function in maltoporin was also assayed, with lactose as a substrate, as previously described (13). The bacteria were grown at 30°C to permit maltoporin expression at the permissive temperature for temperature-sensitive mutants.…”

Section: Methodsmentioning

confidence: 99%

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Genetic analysis of sequences in maltoporin that contribute to binding domains and pore structure

et al. 1988

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Section: Resultsmentioning

confidence: 78%

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 79%

Section: Methodsmentioning

confidence: 99%

See 2 more Smart Citations

Genetic analysis of sequences in maltoporin that contribute to binding domains and pore structure

et al. 1988

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“…A maltodextrin-binding site has been demonstrated (10), and its affinity and specificity correlate well with the transport selectivities and affinities measured in vivo and in vitro (1, 2, 13,17,22). The advantage of maltoporin as a model transport protein is that its binding site is readily amenable to genetic analysis and lamB mutations identifying 16 residues influencing binding and transport selectivity have been defined recently (6,17,18).…”

mentioning

confidence: 96%

Channel architecture in maltoporin: dominance studies with lamB mutations influencing maltodextrin binding provide evidence for independent selectivity filters in each subunit

Ferenci

Lee

1989

J Bacteriol

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Maltoporin trimers constitute maltodextrin-selective channels in the outer membrane of Escherichia coli. To study the organization of the maltodextrin-binding site within trimers, dominance studies were undertaken with maltoporin variants of altered binding affinity. It has been established that amino acid substitutions at three dispersed regions of the maltoporin sequence (at residues 8, 82, and 360) resulted specifically in maltodextrin-binding defects and loss of maltodextrin channel selectivity; a substitution at residue 118 increased both binding affinity and maltodextrin transport. Strains heterodiploid for lamB were constructed in which these substitutions were encoded by chromosomal and plasmid-borne genes, and the relative level of maltoporin expression from these genes was estimated. Binding assays with bacteria forming maltoporin heterotrimers were performed in order to test for complementation between binding-negative alleles, negative dominance of negative over wild-type alleles, and possible dominance of negatives over the high-affinity allele. Double mutants with mutations affecting residues 8 and 118, 82 and 118, and 118 and 360 were constructed in vitro, and the dominance properties of the mutations in cis were also tested. There was no complementation between negatives and no negative dominance in heterotrimers. The high-affinity mutation was dominant over negatives in trans but not in cis. The affinity of binding sites in heterotrimer populations was characteristic of the high-affinity allele present and uninfluenced by the negative allele. These results are consistent with the presence of three discrete binding sites in a maltoporin trimer and suggest that the selectivity filter for maltodextrins is not at the interface between the three subunits.

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Selectivity in solute transport: Binding sites and channel structure in maltoporin and other bacterial sugar transport proteins

Ferenci

1989

BioEssays

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A stereospecific binding site is not the only determinant governing the selectivity of transport proteins. An understanding of transport across cellular membranes requires a description of the different compartments within a transmembrane channel; evidence for the existence of these compartments comes from the selectivity properties of genetically modified maltoporin. Such compartments may also be of significance in determining the specificity of other transport proteins.

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The influence of maltoporin affinity on the transport of maltose and maltohexaose into Escherichia coli

Cited by 8 publications

References 13 publications

Genetic analysis of sequences in maltoporin that contribute to binding domains and pore structure

Genetic analysis of sequences in maltoporin that contribute to binding domains and pore structure

Channel architecture in maltoporin: dominance studies with lamB mutations influencing maltodextrin binding provide evidence for independent selectivity filters in each subunit

Selectivity in solute transport: Binding sites and channel structure in maltoporin and other bacterial sugar transport proteins

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