Mitogenicity of a lipid-deficient lipoprotein from a mutant Escherichia coli strain

Abstract

From the mutant bacterial strain E. coli JE5511 lpp lpm, muropeptide-containing and muropeptide-free lipoproteins were prepared. Gas chromatography and infrared spectroscopy showed that the products were deficient in the 2 ester-bound N-terminal fatty acids, but still carried the amide-linked fatty acid. Mutant lipoproteins were tested for mitogenicity in lipopolysaccharide non-responder C3H/HeJ mice by incorporation of [3H]thymidine and [3H]uridine and by hemolytic plaque assays for immunoglobulin-secreting plasma cells. The mutant lipoproteins still exhibited marked mitogenicity toward mouse B [bone marrow-derived] lymphocytes, although activity of the products was reduced in comparison to the wild-type lipoprotein. The presence of 1 fatty acid in the N-terminal part of lipoprotein is sufficient to bring about mitogenicity.