Influence of cultural conditions and mutations on the composition of the outer membrane proteins ofEscherichia coli

Abstract

VariousEscherichia coli strains differ in the composition of their major outer membrane proteins. However, allE. coli K12 strains tested possess the same major outer membrane proteinsa, b, c andd although quantitative differences were detected. The influence of growth conditions on the composition of the major outer membrane proteins ofE. coli was analyzed. It was found that neither the growth phase at which the cells are harvested, nor the fatty acid composition of the phospholipids has a considerable influence on the composition of these proteins. However, the composition of the growth medium, and, to a less extent, the growth temperature, have a pronounced influence. Certain mutants, changed in the composition of their lipopolysaccharide, are deficient in proteinb. Also mutants deficient in proteinc andd respectively, are described. Proteinsb andc ofE. coli K12 were found to be associated with peptidoglycan. Protein bands, corresponding with flagellin and pilin respectively, were identified.