title: Nanopores: maltoporin channel as a sensor for maltodextrin and lambda-phage.
abstract: BACKGROUND: To harvest nutrition from the outside bacteria e.g. E. coli developed in the outer cell wall a number of sophisticated channels called porins. One of them, maltoporin, is a passive specific channel for the maltodextrin uptake. This channel was also named LamB as the bacterial virus phage Lambda mis-uses this channel to recognise the bacteria. The first step is a reversible binding followed after a lag phase by DNA injection. To date little is known about the binding capacity and less on the DNA injection mechanism. To elucidate the mechanism and to show the sensitivity of our method we reconstituted maltoporin in planar lipid membranes. Application of an external transmembrane electric field causes an ion current across the channel. Maltoporin channel diameter is around a few Angstroem. At this size the ion current is extremely sensitive to any modification of the channels surface. Protein conformational changes, substrate binding etc will cause fluctuations reflecting the molecular interactions with the channel wall. The recent improvement in ion current fluctuation analysis allows now studying the interaction of solutes with the channel on a single molecular level. RESULTS: We could demonstrate the asymmetry of the bacterial phage Lambda binding to its natural receptor maltoporin. CONCLUSION: We suggest that this type of measurement can be used as a new type of biosensors.
authors.affiliation: Institut Pharmacologie & Biologie Structurale-CNRS UMR5089, 205, rte de Narbonne, F-31077 Toulouse, France. m.winterhalter@iu-bremen.de.
authors.forename: E
authors.initials: E
authors.lastname: Berkane
authors.forename: F
authors.initials: F
authors.lastname: Orlik
authors.forename: A
authors.initials: A
authors.lastname: Charbit
authors.forename: C
authors.initials: C
authors.lastname: Danelon
authors.forename: D
authors.initials: D
authors.lastname: Fournier
authors.forename: R
authors.initials: R
authors.lastname: Benz
authors.forename: M
authors.initials: M
authors.lastname: Winterhalter
references.citation: J Biol Chem. 2002 Nov 1;277(44):41318-25
references.pmid: 12185084
references.citation: Biophys J. 2002 Feb;82(2):803-12
references.pmid: 11806922
references.citation: Biophys Chem. 2000 Jul 15;85(2-3):153-67
references.pmid: 10961503
references.citation: Angew Chem Int Ed Engl. 2000 Sep 1;39(17):3137-3140
references.pmid: 11028058
references.citation: Eur J Biochem. 1976 May 17;65(1):13-9
references.pmid: 776623
references.citation: J Biol Chem. 2003 Sep 12;278(37):35542-51
references.pmid: 12835320
references.citation: Mol Microbiol. 1988 Jan;2(1):1-8
references.pmid: 2835584
references.citation: Biochim Biophys Acta. 1978 Aug 17;511(3):305-19
references.pmid: 356882
references.citation: Angew Chem Int Ed Engl. 2004 Feb 6;43(7):842-6
references.pmid: 14767954
references.citation: J Membr Biol. 2000 Mar 1;174(1):1-13
references.pmid: 10741427
references.citation: Structure. 1996 Feb 15;4(2):127-34
references.pmid: 8805519
references.citation: Proc Natl Acad Sci U S A. 1972 Dec;69(12):3561-6
references.pmid: 4509315
references.citation: J Bacteriol. 1975 Oct;124(1):112-8
references.pmid: 1100596
references.citation: Virology. 1976 Jul 1;72(1):182-94
references.pmid: 180667
references.citation: Assay Drug Dev Technol. 2003 Oct;1(5):665-73
references.pmid: 15090239
references.citation: Biophys J. 1999 Dec;77(6):3227-33
references.pmid: 10585944
references.citation: Eur J Biochem. 2000 Jan;267(1):79-84
references.pmid: 10601853
references.citation: J Bacteriol. 1986 Mar;165(3):978-86
references.pmid: 2419312
references.citation: Proc Natl Acad Sci U S A. 2002 Jul 23;99(15):9789-94
references.pmid: 12119404
references.citation: J Bacteriol. 2000 Jan;182(2):508-12
references.pmid: 10629200
references.citation: Biophys J. 1999 Feb;76(2):837-45
references.pmid: 9929485
references.citation: BMC Biotechnol. 2002 May 10;2:9
references.pmid: 12003642