Switches in macromolecular synthesis during induction of competence for transformation of Streptococcus sanguis

Abstract

The induction of synchronous development of competence for genetic transformation in Streptococcus sanguis, by either endogenous or exogenous competence factor (CF), is manifested in the transient synthesis of a new set of at least 10 polypeptides, ranging from 14,000 to 51,000 in molecular weight. Eight polypeptides (E14, E16, E24, E28, E32, E37, E44, E51) appear early, and two polypeptides (L34, L42) appear 5-10 min later. One of the newly synthesized early polypeptides, E16, is shown to be a component of the presynaptic complex containing single-stranded DNA that is produced in vivo upon uptake of native donor DNA. Concomitant with this induced synthesis of competence-specific polypeptides there is a net decrease in RNA and protein synthesis but no change in DNA synthesis; donor DNA-binding ability and transformability reach maxima during the phase of diminishing macromolecular synthesis. Subsequently, donor DNA-binding ability and transformability decay at disproportionate rates as cells return to the normal state of macromolecular synthesis within one generation. Coincident with the induction of competence, the synthesis of a new RNA transcript of high molecular weight appears to be induced which continues during the restricted phase of total cellular RNA synthesis.