The Experts below are selected from a list of 900 Experts worldwide ranked by ideXlab platform
Juan E Suarez - One of the best experts on this subject based on the ideXlab platform.
-
modulation of lactobacillus casei bacteriophage a2 lytic Lysogenic Cycles by binding of gp25 to the early lytic mrna
Molecular Microbiology, 2016Co-Authors: Begona Carrasco, Susana Escobedo, Juan C Alonso, Juan E SuarezAbstract:The genetic switch of Lactobacillus casei bacteriophage A2 is regulated by the CI protein, which represses the early lytic promoter PR and Cro that abolishes expression from the Lysogenic promoter PL . Lysogens contain equivalent cI and cro-gp25 mRNA concentrations, i.e., CI only partially represses P(R), predicting a lytic Cycle dominance. However, A2 generates stable lysogens. This may be due to Gp25 binding to the cro-gp25 mRNA between the ribosomal binding site and the cro start codon, which abolishes its translation. Upon lytic Cycle induction, CI is partially degraded, cro-gp25 mRNA levels increase, and Cro accumulates, launching viral progeny production. The concomitant concentration increase of Gp25 restricts cro mRNA translation, which, together with the low but detectable levels of CI late during the lytic Cycle, promotes reentry of part of the cell population into the Lysogenic Cycle, thus explaining the low proportion of L. casei lysogens that become lysed (∼ 1%). A2 shares its genetic switch structure with many other Firmicutes phages. The data presented may constitute a model of how these phages make the decision for lysis versus lysogeny.
-
differential expression of cro the Lysogenic Cycle repressor determinant of bacteriophage a2 in lactobacillus casei and escherichia coli
Virus Research, 2014Co-Authors: Susana Escobedo, Juan E Suarez, Isabel Rodriguez, Pilar Garcia, Begona CarrascoAbstract:Abstract Expression of bacteriophage A2-encoded cro in Escherichia coli gives rise to two co-linear polypeptides, Cro and Cro*, which were proposed to form a regulatory tandem to modulate the frequency with which the phage would choose between the lytic and the Lysogenic Cycles. In this communication, it is reported that Cro is the canonical product of the gene cro while Cro* results from a −1 ribosome frameshift during translation and is twelve amino acids shorter than Cro. However, frameshifting was not observed during phage development in Lactobacillus casei . Furthermore, wild type phages and cro -frameshifting negative mutants present the same phenotype, thus corroborating that only the canonical form of Cro is needed to produce a viable phage progeny.
-
a2 cro the Lysogenic Cycle repressor specifically binds to the genetic switch region of lactobacillus casei bacteriophage a2
Virology, 1999Co-Authors: Victor Ladero, Juan C Alonso, Juan E Suarez, Pilar GarciaAbstract:Abstract Lysogenic induction of temperate bacteriophage A2 of Lactobacillus casei is controlled by the action of its cI and cro products at the phage operator region. Three 20-bp inverted repeated DNA segments (subsites O 1 , O 2 , and O 3 ) and the two divergent (P L and P R ) promoters were mapped within the 153-bp operator region. The A2-encoded Cro product is shown to be the functional homolog of λ Cro. The binding of Cro to the three operator subsites is noncooperative and yields two discrete protein–DNA complexes of retarded migration in mobility shift assays. The K app value for the Cro–P L –P R DNA complex was estimated to be 6 nM. Cro shows a slightly higher affinity for O 3 than for O 1 and O 2 subsites. The O 3 subsite overlaps the −35 hexamer of the P L promoter, which directs cI expression. A Cro mutant protein, devoid of the last 12 residues (Cro*), allowed the assignment of the DNA-binding domain to the NH 2 end of Cro. The C end enhances its affinity for the DNA and probably stabilizes bending induced by Cro.
Stefan Hertwig - One of the best experts on this subject based on the ideXlab platform.
-
binding specificities of the telomere phage ϕko2 prophage repressor cb and lytic repressor cro
Viruses, 2016Co-Authors: Jens A Hammerl, Claudia Jackel, Erich Lanka, Nicole Roschanski, Stefan HertwigAbstract:Temperate bacteriophages possess a genetic switch which regulates the lytic and Lysogenic Cycle. The genomes of the temperate telomere phages N15, PY54, and ϕKO2 harbor a primary immunity region (immB) comprising genes for the prophage repressor (cI or cB), the lytic repressor (cro) and a putative antiterminator (q). The roles of these products are thought to be similar to those of the lambda proteins CI (CI prophage repressor), Cro (Cro repressor), and Q (antiterminator Q), respectively. Moreover, the gene order and the location of several operator sites in the prototype telomere phage N15 and in ϕKO2 are reminiscent of lambda-like phages. We determined binding sites of the ϕKO2 prophage repressor CB and lytic repressor Cro on the ϕKO2 genome in detail by electrophoretic mobility shift assay (EMSA) studies. Unexpectedly, ϕKO2 CB and Cro revealed different binding specificities. CB was bound to three OR operators in the intergenic region between cB and cro, two OL operators between cB and the replication gene repA and even to operators of N15. Cro bound exclusively to the 16 bp operator site OR3 upstream of the ϕKO2 prophage repressor gene. The ϕKO2 genes cB and cro are regulated by several strong promoters overlapping with the OR operators. The data suggest that Cro represses cB transcription but not its own synthesis, as already reported for PY54 Cro. Thus, not only PY54, but also phage ϕKO2 possesses a genetic switch that diverges significantly from the switch of lambda-like phages.
Begona Carrasco - One of the best experts on this subject based on the ideXlab platform.
-
modulation of lactobacillus casei bacteriophage a2 lytic Lysogenic Cycles by binding of gp25 to the early lytic mrna
Molecular Microbiology, 2016Co-Authors: Begona Carrasco, Susana Escobedo, Juan C Alonso, Juan E SuarezAbstract:The genetic switch of Lactobacillus casei bacteriophage A2 is regulated by the CI protein, which represses the early lytic promoter PR and Cro that abolishes expression from the Lysogenic promoter PL . Lysogens contain equivalent cI and cro-gp25 mRNA concentrations, i.e., CI only partially represses P(R), predicting a lytic Cycle dominance. However, A2 generates stable lysogens. This may be due to Gp25 binding to the cro-gp25 mRNA between the ribosomal binding site and the cro start codon, which abolishes its translation. Upon lytic Cycle induction, CI is partially degraded, cro-gp25 mRNA levels increase, and Cro accumulates, launching viral progeny production. The concomitant concentration increase of Gp25 restricts cro mRNA translation, which, together with the low but detectable levels of CI late during the lytic Cycle, promotes reentry of part of the cell population into the Lysogenic Cycle, thus explaining the low proportion of L. casei lysogens that become lysed (∼ 1%). A2 shares its genetic switch structure with many other Firmicutes phages. The data presented may constitute a model of how these phages make the decision for lysis versus lysogeny.
-
differential expression of cro the Lysogenic Cycle repressor determinant of bacteriophage a2 in lactobacillus casei and escherichia coli
Virus Research, 2014Co-Authors: Susana Escobedo, Juan E Suarez, Isabel Rodriguez, Pilar Garcia, Begona CarrascoAbstract:Abstract Expression of bacteriophage A2-encoded cro in Escherichia coli gives rise to two co-linear polypeptides, Cro and Cro*, which were proposed to form a regulatory tandem to modulate the frequency with which the phage would choose between the lytic and the Lysogenic Cycles. In this communication, it is reported that Cro is the canonical product of the gene cro while Cro* results from a −1 ribosome frameshift during translation and is twelve amino acids shorter than Cro. However, frameshifting was not observed during phage development in Lactobacillus casei . Furthermore, wild type phages and cro -frameshifting negative mutants present the same phenotype, thus corroborating that only the canonical form of Cro is needed to produce a viable phage progeny.
Susana Escobedo - One of the best experts on this subject based on the ideXlab platform.
-
modulation of lactobacillus casei bacteriophage a2 lytic Lysogenic Cycles by binding of gp25 to the early lytic mrna
Molecular Microbiology, 2016Co-Authors: Begona Carrasco, Susana Escobedo, Juan C Alonso, Juan E SuarezAbstract:The genetic switch of Lactobacillus casei bacteriophage A2 is regulated by the CI protein, which represses the early lytic promoter PR and Cro that abolishes expression from the Lysogenic promoter PL . Lysogens contain equivalent cI and cro-gp25 mRNA concentrations, i.e., CI only partially represses P(R), predicting a lytic Cycle dominance. However, A2 generates stable lysogens. This may be due to Gp25 binding to the cro-gp25 mRNA between the ribosomal binding site and the cro start codon, which abolishes its translation. Upon lytic Cycle induction, CI is partially degraded, cro-gp25 mRNA levels increase, and Cro accumulates, launching viral progeny production. The concomitant concentration increase of Gp25 restricts cro mRNA translation, which, together with the low but detectable levels of CI late during the lytic Cycle, promotes reentry of part of the cell population into the Lysogenic Cycle, thus explaining the low proportion of L. casei lysogens that become lysed (∼ 1%). A2 shares its genetic switch structure with many other Firmicutes phages. The data presented may constitute a model of how these phages make the decision for lysis versus lysogeny.
-
differential expression of cro the Lysogenic Cycle repressor determinant of bacteriophage a2 in lactobacillus casei and escherichia coli
Virus Research, 2014Co-Authors: Susana Escobedo, Juan E Suarez, Isabel Rodriguez, Pilar Garcia, Begona CarrascoAbstract:Abstract Expression of bacteriophage A2-encoded cro in Escherichia coli gives rise to two co-linear polypeptides, Cro and Cro*, which were proposed to form a regulatory tandem to modulate the frequency with which the phage would choose between the lytic and the Lysogenic Cycles. In this communication, it is reported that Cro is the canonical product of the gene cro while Cro* results from a −1 ribosome frameshift during translation and is twelve amino acids shorter than Cro. However, frameshifting was not observed during phage development in Lactobacillus casei . Furthermore, wild type phages and cro -frameshifting negative mutants present the same phenotype, thus corroborating that only the canonical form of Cro is needed to produce a viable phage progeny.
Jens A Hammerl - One of the best experts on this subject based on the ideXlab platform.
-
binding specificities of the telomere phage ϕko2 prophage repressor cb and lytic repressor cro
Viruses, 2016Co-Authors: Jens A Hammerl, Claudia Jackel, Erich Lanka, Nicole Roschanski, Stefan HertwigAbstract:Temperate bacteriophages possess a genetic switch which regulates the lytic and Lysogenic Cycle. The genomes of the temperate telomere phages N15, PY54, and ϕKO2 harbor a primary immunity region (immB) comprising genes for the prophage repressor (cI or cB), the lytic repressor (cro) and a putative antiterminator (q). The roles of these products are thought to be similar to those of the lambda proteins CI (CI prophage repressor), Cro (Cro repressor), and Q (antiterminator Q), respectively. Moreover, the gene order and the location of several operator sites in the prototype telomere phage N15 and in ϕKO2 are reminiscent of lambda-like phages. We determined binding sites of the ϕKO2 prophage repressor CB and lytic repressor Cro on the ϕKO2 genome in detail by electrophoretic mobility shift assay (EMSA) studies. Unexpectedly, ϕKO2 CB and Cro revealed different binding specificities. CB was bound to three OR operators in the intergenic region between cB and cro, two OL operators between cB and the replication gene repA and even to operators of N15. Cro bound exclusively to the 16 bp operator site OR3 upstream of the ϕKO2 prophage repressor gene. The ϕKO2 genes cB and cro are regulated by several strong promoters overlapping with the OR operators. The data suggest that Cro represses cB transcription but not its own synthesis, as already reported for PY54 Cro. Thus, not only PY54, but also phage ϕKO2 possesses a genetic switch that diverges significantly from the switch of lambda-like phages.
