Diffusion of solutes through channels produced by phage lambda receptor protein of Escherichiacoli: Inhibition by higher oligosaccharides of maltose series

Luckey, Mary; Nikaido, Hiroshi

doi:10.1016/s0006-291x(80)80261-0

Cited by 82 publications

(45 citation statements)

References 7 publications

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“…This result is consistent with the in vivo situation (8). We do not have a good explanation for the discrepancy between the data of Neuhaus et al (21) and our data, but we stress the fact that the maltotriose binding (which was not found by Neuhaus et al [21]) is identical to the binding found in vivo (11) and in vitro (16).…”

Section: Resultscontrasting

confidence: 97%

“…LamB channels have been shown to be blocked for the penetration of glucose in the presence of maltose or maltodextrins (15,16). In order to measure a similar influence on the conductance induced by LamB in lipid bilayer membranes, single-channel experiments were performed in the presence of maltose and maltodextrins.…”

Section: Resultsmentioning

confidence: 99%

“…Presumably, its diameter does not exceed 0.7 to 0.8 nm, because potassium or chloride ions could not penetrate the channel after the binding of maltose and maltodextrins. It is interesting that both in vivo and in vitro the LamB channel has been found to be blocked in the uptake of substrates by the addition of maltodextrins (8,16).…”

Section: Resultsmentioning

confidence: 99%

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Pore formation by LamB of Escherichia coli in lipid bilayer membranes

Benz¹,

Schmid²,

Nakae³

et al. 1986

J Bacteriol

171

194

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Lipid bilayer experiments were performed in the presence of different Escherichia cofi LamB preparations. These LamB preparations formed two types of pores in the membranes. Large pores, which had a single-channel conductance of 2.7 nS and comprised about 1 to 6% of the total pores, were presumably contaminants which might have been induced together with LamB. LamB itself formed small pores with a single-channel conductance of 160 pS in 1 M KCI. These pores could be completely blocked by the addition of maltose and maltodextrins. Titration of the pore conductance with maltotriose suggested that there was a binding site inside the pores with a Ks of 2.5 x 10-4 M for maltotriose. On the basis of our data we concluded that the structure of the LamB channels is quite different from the structures of the channels of general diffusion porins, such as OmpF and OmpC.

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Section: Resultscontrasting

confidence: 97%

Section: Resultsmentioning

confidence: 99%

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Pore formation by LamB of Escherichia coli in lipid bilayer membranes

Benz¹,

Schmid²,

Nakae³

et al. 1986

J Bacteriol

171

194

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“…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: 78%

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: 97%

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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Diffusion of solutes through channels produced by phage lambda receptor protein of Escherichiacoli: Inhibition by higher oligosaccharides of maltose series

Cited by 82 publications

References 7 publications

Pore formation by LamB of Escherichia coli in lipid bilayer membranes

Pore formation by LamB of Escherichia coli in lipid bilayer membranes

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

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