title: Negative dominance in gene lamB: random assembly of secreted subunits issued from different polysomes.
abstract: lamB is the structural gene for the lambda receptor, an oligomeric outer membrane protein from Escherichia coli K12 involved in phage lambda adsorption. We show that, under certain conditions, in a strain diploid for gene lamB, all the missense lamB mutations conferring lambda resistance that we have tested are dominant with respect to wild-type. We propose a model which allows a quantitative interpretation of the data. It is based on negative complementation at the level of oligomerisation. Wild-type and mutant subunits would assemble at random forming homo- and hetero-oligomers. Only wild-type homo-oligomers would be efficient for phage inactivation. For some classes of missense mutations the hetero-oligomers would have the capacity to bind, but not to inactivate the phage. The model confirms that active lambda receptor is a trimer and implies that for this secreted protein there is no preferential assembly of subunits originating from the same polysome.
authors.affiliation: Unité de Programmation Moléculaire et Toxicologie Génétique, CNRS LA 271, INSERM U.163, Institut Pasteur, Paris, France.
authors.forename: C
authors.initials: C
authors.lastname: Marchal
authors.forename: M
authors.initials: M
authors.lastname: Hofnung
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics; D005798:Genes, Bacterial; D011132:Polyribosomes; D018272:Porins; D011991:Receptors, Virus / Q000235:genetics*
chemical_list: D001425:Bacterial Outer Membrane Proteins; D018272:Porins; D011991:Receptors, Virus; C016532:maltoporins