Specific interaction of fused H protein of bacteriophage phi X174 with receptor lipopolysaccharides

The DNA fragment encoding the spike H protein of bacteriophage phi X174 was amplified by polymerase chain reaction. The fragment was sub-cloned into p QE-30 to yield pQE-H. The histidine-tagged H protein (HisH) was obtained fr om the cell extract of Escherichia coli M15 (pREP4) harboring pQE-H and pur ified by nickel chelating and anion-exchange chromatographies. HisH was sho wn to bind dose-dependently to the lipopolysaccharides (LPSs) isolated from phi X174-sensitive strains, E. Coli C or Salmonella typhimuirum TV119 (Ra mutant). In sharp contrast, HisH did not bind to the LPSs from insensitive strains, E. coli F583 (Rd, mutant) or E. coli O111:B4(smooth strain). Since the same selectivity was observed in the plaque counting assay for in vitr o inactivation of phi X174, the spike H protein was shown to recognize rece ptor LPS. (C) 1999 Elsevier Science B.V. All rights reserved.