title: Docking of a single phage lambda to its membrane receptor maltoporin as a time-resolved event.
abstract: We have been able to observe the first step in bacteriophage infection, the docking of phage lambda to its membrane receptor maltoporin, at the single-particle level. High-resolution conductance recording from a single trimeric maltoporin channel reconstituted into a planar lipid bilayer has allowed detection of the simultaneous and irreversible interaction of the phage tail with all three monomers of the receptor. The formation of a phage-maltoporin complex affects the channel transport properties. Our analysis demonstrates that phage attaches symmetrically to all three receptor monomers. The statistics of sugar binding to the phage-receptor complex on the side opposite to phage docking show that the monomers of maltoporin still bind sugar independently, with the kinetic constants expected from those of the phage-free receptor. This finding suggests that phage docking does not distort the structure of the receptor, and that the phage-binding regions are close to, but do not overlap with, the sugar-binding domains of the maltoporin monomers. However, ion fluxes through the pores of maltoporin in the phage-receptor complex share a new common pathway. We expect that the present study contributes to the current needs for structural information on the functional complexes involved in intercellular recognition.
authors.affiliation: Laboratory of Physical and Structural Biology, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Philip A
authors.initials: PA
authors.lastname: Gurnev
authors.forename: Amos B
authors.initials: AB
authors.lastname: Oppenheim
authors.forename: Mathias
authors.initials: M
authors.lastname: Winterhalter
authors.forename: Sergey M
authors.initials: SM
authors.lastname: Bezrukov
mesh_terms: D001425:Bacterial Outer Membrane Proteins; D010582:Bacteriophage lambda / Q000378:metabolism*; D002241:Carbohydrates / Q000737:chemistry; D004553:Electric Conductivity; D007700:Kinetics; D008051:Lipid Bilayers / Q000378:metabolism; D008954:Models, Biological; D018272:Porins; D011991:Receptors, Virus / Q000378:metabolism*; D013997:Time Factors
chemical_list: D001425:Bacterial Outer Membrane Proteins; D002241:Carbohydrates; D008051:Lipid Bilayers; D018272:Porins; D011991:Receptors, Virus; C016532:maltoporins