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

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Abstract
The induction of synchronous development of competence for genetic transformation in S. 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 14,000-51,000 in MW. Eight polypeptides (E14, E16, E24, E28, E32, E37, E44, E51) appear early, and 2 polypeptides (L34, L42) appear 5-10 min later. One of the newly synthesized early polypeptides, E16, is 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 1 generation. Coincident with the induction of competence, the synthesis of a new RNA transcript of high MW appears to be induced which continues during the restricted phase of total cellular RNA synthesis.