Defective membrane synthesis in an E. coli mutant

Abstract

THERE is a strict correlation between DNA synthesis and cell division^1,2 but there is no known relationship between cell division and membrane synthesis—presumably because so little is known about the latter. We have previously reported that the formation of cytochrome b₁ and the L–α–glycerophosphate uptake system occurs at the same time (in a discontinuous manner) at a particular phase in a cell cycle of Escherichia coli (ref. 3). On the basis of these observations we attempted to isolate a phase-specific mutant which has a defect in the formation of membrane components. The selection of the mutants was carried out assuming that cell growth is temperature-sensitive and that the formation of the β-galactoside transport system is under the control of the corresponding ts-mutation. These assumptions were based on the observation that the formation of the transport system for β-galactoside, measured using a synchronous culture, completely coincided with those of many membrane components including cytochrome b₁ (M.O., unpublished) and on the consideration that cells defective for such processes should be non-viable⁴.