CLONING OF THE J GENE OF BACTERIOPHAGE-LAMBDA, EXPRESSION AND SOLUBILIZATION OF THE J-PROTEIN - FIRST IN-VITRO STUDIES ON THE INTERACTIONS BETWEEN J AND LAMB, ITS CELL-SURFACE RECEPTOR

Bacteriophage lambda adsorbs to its Escherichia coil K12 host by inter acting with a specific cell surface receptor, the outer membrane prote in LamB. Previous genetic analyses led us to define a set of residues at the surface of LamB, which belong to the lambda receptor site. Furt her genetic studies indicated that the C-terminal portion of J, the ta il fibre protein of lambda, was directly involved in the recognition o f the receptor site. The present work describes first in vitro studies on the interactions between J and Lamb. The J gene of lambda was clon ed into a plasmid vector under ptac promoter control and expressed in E. coil. We showed that J could be expressed at high levels (up to 28% of whole cell proteins), in an insoluble form. Anti-J antibodies, ind uced in rabbits immunized with insoluble J extracts, appeared to speci fically neutralize lambda infection. Under defined conditions of extra ction, the J protein was obtained in a soluble form. We showed that so lubilized J was able to interact with Lamb trimers in vitro. Implicati ons for future studies on the interactions between Lamb and J are disc ussed.