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  Properties of a cyclodextrin-specific, unusual porin from Klebsiella oxytoca

Pajatsch, M., Andersen, C., Mathes, A., Böck, A., Benz, R., & Engelhardt, H. (1999). Properties of a cyclodextrin-specific, unusual porin from Klebsiella oxytoca. Journal of Biological Chemistry, 274(35), 25159-25166.

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Genre: Journal Article
Alternative Title : J. Biol. Chem

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Pajatsch, M., Author
Andersen, C., Author
Mathes, A., Author
Böck, A., Author
Benz, R., Author
Engelhardt, H.1, Author              
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1External Organizations, ou_persistent22              

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Free keywords: Outer-membrane proteins; Escherichia-coli; Comamonas-acidovorans; 3-d reconstruction; Surface protein; Cloning vectors; Current noise; Transport; Binding; Channel.; Biochemistry & Biophysics in Current Contents(R)/Life Sciences.
 Abstract: The function of CymA, 1 of the 10 gene products involved in cyclodextrin uptake and metabolism by Klebsiella oxytoca, was characterized. CymA is essential for growth on cyclodextrins, but it can also complement the deficiency of a lamB (maltoporin) mutant of Escherichia coil for growth on linear maltodextrins, indicating that both cyclic and linear oligosaccharides are accepted as substrates, CymA was overproduced in E. coli and purified to apparent homogeneity. CymA is a component of the outer membrane, is processed from a signal peptide-containing precursor, and possesses a high content of antiparallel beta-sheet. Incorporation of CymA into lipid bilayers and conductance measurements revealed that it forms ion-permeable channels, which exhibit a substantial current noise. CymA-induced membrane conductance decreased considerably upon addition of cu-cyclodextrin, Titration experiments allowed the calculation of a half-saturation constant, K-S, of 28 mu M for its binding to CymA. CymA assembled in vitro to two-dimensionally crystalline tubular membranes, which, on electron microscopy, are characterized by a p1-related two-sided plane group. The crystallographic unit cell contains four monomeric CymA molecules showing a central pore. The lattice parameters are a = 16.1 nn, b = 3.8 nm, gamma = 93 degrees. CymA does not form trimeric complexes in lipid membranes and shows no tendency to trimerize in solution. CymA thus is an atypical porin with novel properties specialized to transfer cyclodextrins across the outer membrane. [References: 50]

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 Dates: 1999
 Publication Status: Published in print
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 Identifiers: eDoc: 318438
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Title: Journal of Biological Chemistry
  Alternative Title : J. Biol. Chem
Source Genre: Journal
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Pages: - Volume / Issue: 274 (35) Sequence Number: - Start / End Page: 25159 - 25166 Identifier: -