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Crystal structures of various maltooligosaccharides bound to maltoporin reveal a specific sugar translocation pathway


Dutzler, R; Wang, Y F; Rizkallah, P; Rosenbusch, J P; Schirmer, T (1996). Crystal structures of various maltooligosaccharides bound to maltoporin reveal a specific sugar translocation pathway. Structure, 4(2):127-34.

Abstract

BACKGROUND: Maltoporin (which is encoded by the lamB gene) facilitates the translocation of maltodextrins across the outer membrane of E. coli. In particular, it is indispensable for the transport of long maltooligosaccharides, as these do not pass through non-specific porins. An understanding of this intriguing capability requires elucidation of the structural basis. RESULTS: The crystal structures of maltoporin in complex with maltose, maltotriose and maltohexaose reveal an extended binding site within the maltoporin channel. The maltooligosaccharides are in apolar van der Waals contact with the 'greasy slide', a hydrophobic path that is composed of aromatic residues and located at the channel lining. At the constriction of the channel the sugars are tightly surrounded by protein side chains and form an extensive hydrogen-bonding network with ionizable amino-acid residues. CONCLUSION: Hydrophobic interactions with the greasy slide guide the sugar into and through the channel constriction. The glucosyl-binding subsites at the channel constriction confer stereospecificity to the channel along with the ability to scavenge substrate at low concentrations.

Abstract

BACKGROUND: Maltoporin (which is encoded by the lamB gene) facilitates the translocation of maltodextrins across the outer membrane of E. coli. In particular, it is indispensable for the transport of long maltooligosaccharides, as these do not pass through non-specific porins. An understanding of this intriguing capability requires elucidation of the structural basis. RESULTS: The crystal structures of maltoporin in complex with maltose, maltotriose and maltohexaose reveal an extended binding site within the maltoporin channel. The maltooligosaccharides are in apolar van der Waals contact with the 'greasy slide', a hydrophobic path that is composed of aromatic residues and located at the channel lining. At the constriction of the channel the sugars are tightly surrounded by protein side chains and form an extensive hydrogen-bonding network with ionizable amino-acid residues. CONCLUSION: Hydrophobic interactions with the greasy slide guide the sugar into and through the channel constriction. The glucosyl-binding subsites at the channel constriction confer stereospecificity to the channel along with the ability to scavenge substrate at low concentrations.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > Department of Biochemistry
07 Faculty of Science > Department of Biochemistry
Dewey Decimal Classification:570 Life sciences; biology
Language:English
Date:1996
Deposited On:17 Mar 2009 11:29
Last Modified:20 Feb 2018 08:47
Publisher:Elsevier
ISSN:0969-2126
OA Status:Closed
Publisher DOI:https://doi.org/10.1016/S0969-2126(96)00016-0
PubMed ID:8805519

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