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OmpW of Caulobacter crescentus functions as an outer membrane channel for cations

Please always quote using this URN: urn:nbn:de:bvb:20-opus-145114
  • Caulobacter crescentus is an oligotrophic bacterium that lives in dilute organic environments such as soil and freshwater. This bacterium represents an interesting model for cellular differentiation and regulation because daughter cells after division have different forms: one is motile while the other is non-motile and can adhere to surfaces. Interestingly, the known genome of C. crescentus does not contain genes predicted to code for outer membrane porins of the OmpF/C general diffusion type present in enteric bacteria or those coding forCaulobacter crescentus is an oligotrophic bacterium that lives in dilute organic environments such as soil and freshwater. This bacterium represents an interesting model for cellular differentiation and regulation because daughter cells after division have different forms: one is motile while the other is non-motile and can adhere to surfaces. Interestingly, the known genome of C. crescentus does not contain genes predicted to code for outer membrane porins of the OmpF/C general diffusion type present in enteric bacteria or those coding for specific porins selective for classes of substrates. Instead, genes coding for 67 TonB-dependent outer membrane receptors have been identified, suggesting that active transport of specific nutrients may be the norm. Here, we report that high channel-forming activity was observed with crude outer membrane extracts of C. crescentus in lipid bilayer experiments, indicating that the outer membrane of C. crescentus contained an ion-permeable channel with a single-channel conductance of about 120 pS in 1M KCl. The channel-forming protein with an apparent molecular mass of about 20 kDa was purified to homogeneity. Partial protein sequencing of the protein indicated it was a member of the OmpW family of outer membrane proteins from Gram-negative bacteria. This channel was not observed in reconstitution experiments with crude outer membrane extracts of an OmpW deficient C. crescentus mutant. Biophysical analysis of the C. crescentus OmpW suggested that it has features that are special for general diffusion porins of Gram-negative outer membranes because it was not a wide aqueous channel. Furthermore, OmpW of C. crescentus seems to be different to known OmpW porins and has a preference for ions, in particular cations. A putative model for OmpW of C. crescentus was built on the basis of the known 3D-structures of OmpW of Escherichia coli and OprG of Pseudomonas aeruginosa using homology modeling. A comparison of the two known structures with the model of OmpW of C. crescentus suggested that it has a more hydrophilic interior and possibly a larger diameter.show moreshow less

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Metadaten
Author: Roland Benz, Michael D. Jones, Farhan Younas, Elke Maier, Niraj Modi, Reinhard Mentele, Friedrich Lottspeich, Ulrich Kleinekathöfer, John Smit
URN:urn:nbn:de:bvb:20-opus-145114
Document Type:Journal article
Faculties:Fakultät für Biologie / Rudolf-Virchow-Zentrum
Language:English
Parent Title (English):PLoS ONE
Year of Completion:2015
Volume:10
Issue:11
Pagenumber:e0143557
Source:PLoS ONE 10(11): e0143557 (2015). DOI: 10.1371/journal.pone.0143557
DOI:https://doi.org/10.1371/journal.pone.0143557
Dewey Decimal Classification:6 Technik, Medizin, angewandte Wissenschaften / 61 Medizin und Gesundheit / 610 Medizin und Gesundheit
Tag:S-layer protein; amino acid sequence; cell wall; escherichia coli; ionic selectivity; lipid bilayer membranes; matrix protein porin; molecular basis; pseudomonas aeruginosa; selective channel
Release Date:2018/11/05
EU-Project number / Contract (GA) number:FP7/2007-2013
OpenAIRE:OpenAIRE
Licence (German):License LogoCC BY: Creative-Commons-Lizenz: Namensnennung 4.0 International