Cellular Metabolism in Genetic Transformation of Pneumococci: Requirement for Protein Synthesis During Induction of Competence
01 Mar 1970-Journal of Bacteriology (American Society for Microbiology)-Vol. 101, Iss: 3, pp 860-871
TL;DR: Evidence is presented suggesting that, in addition to the competence factor, another specific protein or class of proteins is essential for the development of cellular "competence" in pneumococci.
Abstract: Metabolic inhibitors have differential effects on various phases of genetic transformation in pneumococci. Evidence is presented suggesting that, in addition to the competence factor, another specific protein or class of proteins is essential for the development of cellular “competence.” The precise role of this protein(s) in genetic transformation is not known, but it seems essential for some function subsequent to the interaction of competence factor and cells.
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TL;DR: It is shown that strain CP1200 produces a 17-residue peptide that induces cells of the Streptococcus pneumoniae species to develop competence and the hypothesis is presented that this transport protein is encoded by comA, previously shown to be required for elaboration of the pneumococcal competence activator.
Abstract: Competence for genetic transformation in Streptococcus pneumoniae has been known for three decades to arise in growing cultures at a critical cell density, in response to a secreted protease-sensitive signal. We show that strain CP1200 produces a 17-residue peptide that induces cells of the species to develop competence. The sequence of the peptide was found to be H-Glu-Met-Arg-Leu-Ser-Lys-Phe-Phe-Arg-Asp-Phe-Ile-Leu-Gln-Arg- Lys-Lys-OH. A synthetic peptide of the same sequence was shown to be biologically active in small quantities and to extend the range of conditions suitable for development of competence. Cognate codons in the pneumococcal chromosome indicate that the peptide is made ribosomally. As the gene encodes a prepeptide containing the Gly-Gly consensus processing site found in peptide bacteriocins, the peptide is likely to be exported by a specialized ATP-binding cassette transport protein as is characteristic of these bacteriocins. The hypothesis is presented that this transport protein is encoded by comA, previously shown to be required for elaboration of the pneumococcal competence activator.
746 citations
TL;DR: It is demonstrated that CRISPR interference can prevent the emergence of virulence in vivo and that strong selective pressure for virulence or antibiotic resistance can lead toCRISPR loss in bacterial pathogens.
320 citations
Cites background from "Cellular Metabolism in Genetic Tran..."
...The crR6 strain contains the aphA-3 gene (providing for kanamycin resistance) linked to the CRISPR locus as well as an unlinked rpsL allele that confers streptomycin resistance (Tomasz, 1970), and which selection serves as a transformation control....
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..., 2001), R6 (Tomasz, 1970), and SV36 (Nesin et al....
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TL;DR: Multiply drug-resistant South African pneumococci showed several types of major alterations in their penicillin-binding protein (PBP) pattern compared with that of a penicillus-susceptible laboratory strain of Streptococcus pneumoniae.
Abstract: Multiply drug-resistant South African pneumococci (with penicillin minimal inhibitory concentrations ranging from 0.2 to 12.5 microgram/ml) showed several types of major alterations in their penicillin-binding protein (PBP) pattern compared with that of a penicillin-susceptible laboratory strain of Streptococcus pneumoniae (R6; penicillin minimal inhibitory concentration = 0.006 microgram/ml). Genetic transformants were obtained by using South African pneumococcus (strain 8249) deoxyribonucleic acid as donor and the competent cells of strain R6 as recipient; seven classes of transformants with progressively higher penicillin resistance were isolated, and their PBPs were tested. The PBP patterns exhibited a gradual shift from a pattern similar to that of the recipient to a pattern resembling that of the donor strain as the level of penicillin resistance increased.
258 citations
Cites methods from "Cellular Metabolism in Genetic Tran..."
...Culture growth was monitored by nephelometry (20), using a Coleman nephocolorimeter....
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...0 (20) supplemented with yeast extract (Difco Laboratories; final concentration, 1 mg per ml of growth medium)....
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TL;DR: Transformation experiments suggest that ParC is the primary target of ciprofloxacin, and mutation in parC appears to be a prerequisite before mutations in gyrA can influence resistance levels.
Abstract: The genes encoding the ParC and ParE subunits of topoisomerase IV of Streptococcus pneumoniae, together with the region encoding amino acids 46 to 172 (residue numbers are as in Escherichia coli) of the pneumococcal GyrA subunit, were partially characterized. The gyrA gene maps to a physical location distant from the gyrB and parC loci on the chromosome, whereas parC is closely linked to parE. Ciprofloxacin-resistant (Cpr) clinical isolates of S. pneumoniae had mutations affecting amino acid residues of the quinolone resistance-determining region of ParC (low-level Cpr) or in both quinolone resistance-determining regions of ParC and GyrA (high-level Cpr). Mutations were found in residue positions equivalent to the serine at position 83 and the aspartic acid at position 87 of the E. coli GyrA subunit. Transformation experiments suggest that ParC is the primary target of ciprofloxacin. Mutation in parC appears to be a prerequisite before mutations in gyrA can influence resistance levels.
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TL;DR: Transformable streptococci produce an exocellular factor provoking competence under certain conditions, and non-competent cultures become competent upon addition of this factor.
Abstract: SUMMARY Transformable streptococci produce an exocellular factor provoking competence under certain conditions. Non-competent cultures become competent upon addition of this factor. The kinetics of conversion is concomitant with an enzymic reaction; the process is time and temperature dependent and the factor itself is heat sensitive. The action of the hypothetical enzyme on cells of a non-transformable streptococcus results in provocation of competence.
201 citations
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