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

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

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

T Ferenci,K S Lee,

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.

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

T Ferenci,KS Lee,

For similar proteins: membrane proteins: receptors, cell surface: receptors, virus research abstracts see: proteins: membrane proteins: receptors, cell surface: receptors, virus research

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

PUBLICATION TYPE: Research Support, Non-U.S. Gov

Journal: Journal of bacteriology

VOLUME: 171

Page Numbers: 855-61

Journal Abbreviation: J. Bacteriol.

ISSN: 0021-9193

DAY: 27

MONTH: Feb

YEAR: 1989

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

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LANGUAGE: eng

NlmUniqueID: 2985120

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

KEYWORDS: Receptors, Virus

MESH TERMS: genetics

Chemical & Substance for Abstract: Channel architecture in maltoporin: dominance studies with lamB mutations influencing maltodextrin binding provide evidence for independent selectivity filters in each subunit. Information

Substance Name: maltodextrin

Registry Number: 9050-36-6

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

AFFILIATION: Department of Microbiology, University of Sydney, New South Wales, Australia.

Country: UNITED STATES

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MEDLINETA: J Bacteriol

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