Requirement for membrane potential in injection of phage T4 DNA.

Abstract
The 1st stages of infection [of Escherichia coli] by phage T4 may be divided into energy-dependent and energy-independent processes. Irreversible adsorption, unplugging and initial exposure of the DNA terminus may occur at 4.degree. C, or at 37.degree. C in bacteria whose energy-yielding metabolism has been poisoned. DNA injection into the cytoplasm needs higher temperatures and energy from the host cell. The nature of this energy requirement was deduced from the use of metabolic inhibitors. T4 DNA injection specifically requires the presence of a protonmotive force across the cytoplasmic membrane of the host. The chemical gradient (.DELTA.pH) does not appear to be essential, but the membrane potential (.DELTA..psi.) is required.