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 Genetic transformation in many species of bacteria is dependent on a transiently acquired physiological state, called competence, of the recipient cells. Competence confers upon cells the ability to bind native DNA from the environment. Binding culminates, after a series of events, in the integration and expression of the exogenous DNA (1-3). The competent state is elicited in some bacterial strains by the synthesis of a small protein (competence factor or CF) which triggers a synchronous response in cells to undergo competence (4,5). CF can be collected and purified from the supernatant of a competent population and, when added exogenously, can induce competence in physiologically noncompetent cells of the same or closely related species (6). These inductions require protein synthesis (7).In Bacillus subtilis, development of competence is restricted to a small, biosynthetically inactive fraction (<20%) of the cell population (8), whereas in Streptococcus sanguis (9) and S. pneumoniae (10) nearly the entire population becomes competent for a short time during exponential growth. Until recently, no significant changes in overall macromolecular synthesis (11) have been detected in the latter group of species. Although induction of new proteins during development of competence has been demonstrated (12), more recent evidence indicates that protein synthesis during the development of competence in S. pneumontae is restricted to a new set of 11 principal species (13).The publication costs of this article were defrayed in part by page charge payment. This article must therefore by hereby marked "advertisement" in accordance with 18 U. S. Macromolecular Synthesis. Cell samples removed from competence medium at various time intervals, in volumes to contain 1-2 X 108 colony-forming units (CFU) were pelleted, washed with chilled synthetic medium, and labeled for 10 min at 370C in 0.5 ml of synthetic medium supplemented with[3H]leucine (40 ,gCi/ml; 1 Ci = 3.7 X 1010 becquerels), [3H]-uridine (100,gCi/ml), or [3H]thymidine (20,MCi/ml). A portion from each sample was deposited on a filter disc (glass microfiber, GF/A). Each filter disc was then immersed in 10 ml of ice-cold 10% trichloroacetic acid for 4 hr. washed with 150 ml of 5% trichloroacetic acid and then 50 ml of ethanol, dried, and assayed for radioactivity.Competence. Cells in 0.5 ml of synthetic medium were incubated for 8 min and exposed to 1 /,tg of [3H]thymidine-labeled S. sanguis str-r43 (streptomycin-resistant) DNA (specific activity, 2.0-2.2 X 105 cpm/Ag) for 1 min. DNA uptake was terminated by addition of DNase 1 (20 ,u...

Modulation of Competence for Genetic Transformation in Streptococcus pneumoniae

“…Competence in Streptococcuspneumoniae is associated with the induction of a small set of new proteins (Morrison & Baker, 1979; Morrison, 1981), temporary cessation of synthesis of most other proteins, and the appearance of a number of unusual cell properties, including an efficient system for taking up DNA and promoting genetic recombination between that DNA and the cell chromosome (Avery et A similar protein shift occurs in Streptococcus sanguis (Raina & Ravin, 1980). The drastic protein shift seen in competent cultures suggests that nearly all cells participate in the redirection of protein synthesis accompanying competence.…”

Calcium regulation of growth and differentiation in Streptococcus pneumoniae

“…Competent bacteria exhibit new properties with regard to surface antigens (Nava et al, 1963), membrane nuclease activity (Lacks & Greenberg, 1973;Lacks & Neuberger, 1975), DNA transport (Lerman 8z Tolmach, 1957), recombination and repair (Love & Yasbin, 1986), expression of a set of specific proteins (Morrison & Baker, 1979;Raina & Ravin, 1980) and synthesis of the lipid polymer poly(P-hydroxybutyrate) (Reusch & Sadoff, 1983 ; ClavC et al, 1989). Membrane hyperpolarization (Trombe, 1983), as well as a stimulation of glycolysis associated with an increased ATP pool and a cytoplasmic alkalinization (Lopez et al, 1989), are observed in competent S .…”

Characterization of genetic transformation in Streptococcus mutans by using a novel high-efficiency plasmid marker rescue system

“…sanguis is a member of a small group of gram-positive bacteria that are naturally transformable (31). Competence in this organism appears to be inducible, as suggested by biological (13) and molecular (28) experiments. A lowmolecular-weight polypeptide is responsible for competence induction and has been termed the competence factor (CF) (14,23).…”