The in vivo formation of nonbilayer lipid phase in E. coli membranes during the development of Ca2-dependent competence.

31P-NMR studies on E. coli cells reveal the in vivo formation of nonbilayer lipid structures, presumably of H11 phase, during Ca2-dependent competence induction. The data suggest the involvement of these structures in the exogenous DNA transfer into the cells during genetic transformation and transfection. The suggestion is supported by in vitro experiments in which the liposomes composed of different phospholipid species bind 14C-DNA in DNase and wash resistant form in conditions promoting the hexagonal phase formation.