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A sugar‐specific porin, ScrY, is involved in sucrose uptake in enteric bacteria

A sugar‐specific porin, ScrY, is involved in sucrose uptake in enteric bacteria Summary During the molecular analysis of a plasmid‐coded sucrose metabolic pathway of enteric bacteria, a gene, scrY, was found whose product, ScrY, had all the properties of a bacterial porin (Schmid et al, 1988). Loss of this protein (Mr 58kDa), localized in the outer membrane, led, as shown here, to an increase in the apparent Km for sucrose transport in whole cells from 10 μM in wild‐type cells to 300 μM in mutant cells. This contrasts with the Km for sucrose phosphorylation as measured in membrane vesicles from mutant and wild‐type cells, which remained unchanged at about 10 μM, and reflects the activity of the sucrose‐specific Enzymell of the phosphoenolpyruvate‐dependent carbohydrate:phosphotransferase system (PTS) responsible for uptake through the inner membrane. Furthermore, the presence of ScrY restored growth on maltodextrins in cells devoid of LamB, thus complementing the lack of this maltoporin. The amino acid sequence deduced from the DNA sequence was determined for the plasmid‐coded and the ScrY porin coded in the chromosome of Klebsiella pneumoniae. Both show high identity (86%) to each other, and to the channel domain of LamB, further corroborating the conclusion that they constitute porins. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Molecular Microbiology Wiley

A sugar‐specific porin, ScrY, is involved in sucrose uptake in enteric bacteria

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References (43)

Publisher
Wiley
Copyright
Copyright © 1991 Wiley Subscription Services, Inc., A Wiley Company
ISSN
0950-382X
eISSN
1365-2958
DOI
10.1111/j.1365-2958.1991.tb00769.x
Publisher site
See Article on Publisher Site

Abstract

Summary During the molecular analysis of a plasmid‐coded sucrose metabolic pathway of enteric bacteria, a gene, scrY, was found whose product, ScrY, had all the properties of a bacterial porin (Schmid et al, 1988). Loss of this protein (Mr 58kDa), localized in the outer membrane, led, as shown here, to an increase in the apparent Km for sucrose transport in whole cells from 10 μM in wild‐type cells to 300 μM in mutant cells. This contrasts with the Km for sucrose phosphorylation as measured in membrane vesicles from mutant and wild‐type cells, which remained unchanged at about 10 μM, and reflects the activity of the sucrose‐specific Enzymell of the phosphoenolpyruvate‐dependent carbohydrate:phosphotransferase system (PTS) responsible for uptake through the inner membrane. Furthermore, the presence of ScrY restored growth on maltodextrins in cells devoid of LamB, thus complementing the lack of this maltoporin. The amino acid sequence deduced from the DNA sequence was determined for the plasmid‐coded and the ScrY porin coded in the chromosome of Klebsiella pneumoniae. Both show high identity (86%) to each other, and to the channel domain of LamB, further corroborating the conclusion that they constitute porins.

Journal

Molecular Microbiology – Wiley

Published: Apr 1, 1991

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