EFFECT OF MUTATIONS IN SURFACE LIPOPOLYSACCHARIDE OR OUTER MEMBRANE PROTEIN OF ESCHERICHIA COLI C ON TRANSFECTING COMPETENCE FOR MICROVIRID PHAGE DNA

Abstract

Ca²⁺- or Ba²⁺-dependent uptake of microvirid phage DNA was not affected by the presence or absence of a phage receptor on the cell surface of E. coli C. Structural changes of cell wall lipopolysaccharide in E. coli C, however, affected the development of Ca²⁺- or Ba²⁺-dependent competence. Thus, efficiency of transfection was low in strain C61 (lacking branch heptose) and in C23•1 (deficient in galactose residues and branch glucose). Ba²⁺-induced competence was low in the terminal galactose-less strain C23 as well. Deficiency in murein lipoprotein resulted in an increased competence for single-stranded DNA and double-stranded replicative form DNA. Level of the competence of mutants resistant to T5 and/or T1 was not much different from that of the sensitive bacteria. In various strains of E. coli, Ca²⁺ (Ba²⁺)-induced competence for single-stranded DNA was parallel with that for double-stranded replicative form DNA. On the other hand, the ratio of Ca²⁺- and the Ba²⁺-dependent competence varied considerably in several derivatives of strain C.