scholarly journals Interaction of the Cro repressor with the lysis/lysogeny switch of the Lactobacillus casei temperate bacteriophage A2

2002 ◽  
Vol 83 (11) ◽  
pp. 2891-2895 ◽  
Author(s):  
Victor Ladero ◽  
Pilar García ◽  
Juan C. Alonso ◽  
Juan E. Suárez
Keyword(s):  
Lactobacillus Casei ◽  
Dna Looping ◽  
Lytic Cycle ◽  
Temperate Bacteriophage ◽  
Switch Region ◽  
Genetic Switch ◽  
Divergent Promoters ◽  
Phage Development ◽  
Transcriptional Switch ◽  
Late Stages

The transcriptional switch region of Lactobacillus casei temperate bacteriophage A2 contains three similar 20 bp operator subsites, O1, O2 and O3, which are interspersed between the divergent promoters P R and P L. The Cro protein binds initially to O3, which overlaps the −35 region of P L, excluding the RNA polymerase (σA-RNAP) from it. This results in the switching off of cI transcription and directs the incoming phage into the lytic cycle. At higher concentrations, Cro also binds to O1 and/or O2, which overlap P R, probably introducing a bend in the intervening DNA. This interaction induces DNA looping, which provokes the subsequent displacement of σA-RNAP from P R. Consequently, Cro abolishes the binding of σA-RNAP to the genetic switch of A2 and, presumably, its own synthesis, contributing indirectly to the entry of phage development into its late stages.

scholarly journals A2 Cro, the Lysogenic Cycle Repressor, Specifically Binds to the Genetic Switch Region of Lactobacillus casei Bacteriophage A2

Virology ◽  
1999 ◽  
Vol 262 (1) ◽  
pp. 220-229 ◽  
Author(s):  
Victor Ladero ◽  
Pilar García ◽  
Juan C. Alonso ◽  
Juan E. Suárez
Keyword(s):  
Lactobacillus Casei ◽  
Switch Region ◽  
Genetic Switch

scholarly journals A Complex Genetic Switch Involving Overlapping Divergent Promoters and DNA Looping Regulates Expression of Conjugation Genes of a Gram-positive Plasmid

PLoS Genetics ◽  
2014 ◽  
Vol 10 (10) ◽  
pp. e1004733 ◽  
Author(s):  
Gayetri Ramachandran ◽  
Praveen K. Singh ◽  
Juan Roman Luque-Ortega ◽  
Luis Yuste ◽  
Carlos Alfonso ◽  
...  
Keyword(s):  
Dna Looping ◽  
Gram Positive ◽  
Genetic Switch ◽  
Divergent Promoters

Studies on the gene regulation involved in the lytic–lysogenic switch in Staphylococcus aureus temperate bacteriophage Phi11

2020 ◽  
Vol 168 (6) ◽  
pp. 659-668
Author(s):  
Avijit Das ◽  
Sukhendu Mandal ◽  
Vijay Hemmadi ◽  
Vivek Ratre ◽  
Malabika Biswas
Keyword(s):  
Staphylococcus Aureus ◽  
Gene Regulation ◽  
Genome Sequence ◽  
Crucial Role ◽  
Lytic Cycle ◽  
Temperate Bacteriophage ◽  
Developmental Pathway ◽  
Prophage Induction ◽  
Repressor Protein ◽  
Cro Repressor

Abstract Antirepressor proteins of bacteriophages are chiefly involved in interfering with the function of the repressor protein and forcing the bacteriophage to adopt the lytic cycle. The genome of Staphylococcus aureus phage, Phi11 has already been sequenced; from the genome sequence, we amplified gp07 gene and analysed its involvement in the developmental pathway of Phi11. Our results indicate that Gp07 functions as a novel antirepressor and regulates the developmental pathway of Phi11 by enhancing the binding of the Cro repressor protein to its cognate operator. We also report our finding that the CI repressor protein of Phi11 binds to the putative operator of Gp07 and regulates its expression. We further report that S.aureus transcriptional repressor LexA and coprotease RecA play a crucial role in the lytic–lysogenic switching in Phi11. We also identified that the N-terminal domain (Bro-N) of Gp07 is actually responsible for enhancing the binding of Cro repressor to its cognate operator. Our results suggest that Phi11 prophage induction is different from other bacteriophages. This study furnishes a first-hand report regarding the regulation involved in the developmental pathway of Phi11.

scholarly journals Lack of the host membrane protease FtsH hinders release of the Lactococcus lactis bacteriophage TP712

2013 ◽  
Vol 94 (12) ◽  
pp. 2814-2818 ◽  
Author(s):  
Clara Roces ◽  
Udo Wegmann ◽  
Ana B. Campelo ◽  
Pilar García ◽  
Ana Rodríguez ◽  
...  
Keyword(s):  
Lactococcus Lactis ◽  
Dna Delivery ◽  
Lytic Cycle ◽  
Temperate Bacteriophage ◽  
Thin Sections ◽  
Phage Adsorption ◽  
Host Membrane ◽  
Phage Dna ◽  
In Trans

The temperate bacteriophage TP712 was unable to plaque on Lactococcus lactis ΔftsH lacking the membrane protease FtsH and complementation in trans restored the WT phenotype. Absence of ftsH did not hinder phage adsorption, phage DNA delivery or activation of the lytic cycle. Thin sections revealed that TP712 virions appeared to be correctly assembled inside the ΔftsH host, but were not released. These virions were infective, demonstrating that a functional host FtsH is required by TP712 to proceed effectively with lysis of the host.

scholarly journals The Natural Flavonoid Compound Deguelin Inhibits HCMV Lytic Replication within Fibroblasts

2018 ◽  
Author(s):  
Masatoshi Nuikui ◽  
Christine M. O'Connor ◽  
Eain A. Murphy
Keyword(s):  
Infectious Virus ◽  
Lytic Replication ◽  
Lytic Cycle ◽  
Flavonoid Compound ◽  
Therapeutic Resistance ◽  
Naturally Occurring ◽  
Gene And Protein Expression ◽  
Latently Infected ◽  
Hcmv Replication ◽  
Late Stages

Human cytomegalovirus (HCMV) is a ubiquitous herpesvirus, for which there is no vaccine or cure. This viral infection, once acquired, is life-long, residing latently in hematopoietic cells. However, latently infected individuals with weakened immune systems often undergo HCMV reactivation, which can cause serious complications in immunosuppressed and immunocompromised patients. Current anti-viral therapies target late stages of viral replication, and are often met with therapeutic resistance, necessitating the development of novel therapeutics. In this current study, we identified a naturally occurring flavonoid compound, deguelin, which inhibits HCMV lytic replication. Our findings reveal that nanomolar concentrations of deguelin significantly suppress the production of infectious virus. Further, we show that deguelin inhibits the lytic cycle during the phase of the replication cycle consistent with early (E) gene and protein expression. Importantly, our data reveal that deguelin inhibits replication of a ganciclovir-resistant strain of HCMV. Together, our findings identify a novel, naturally occurring compound that may prove useful in the treatment of HCMV replication.

scholarly journals Complete genomic sequence of the temperate bacteriophage ΦAT3 isolated from Lactobacillus casei ATCC 393

Virology ◽  
2005 ◽  
Vol 339 (1) ◽  
pp. 42-55 ◽  
Author(s):  
Ta-Chun Lo ◽  
Tsung-Chieh Shih ◽  
Chao-Fen Lin ◽  
Hung-Wen Chen ◽  
Thy-Hou Lin
Keyword(s):  
Lactobacillus Casei ◽  
Genomic Sequence ◽  
Complete Genomic Sequence ◽  
Temperate Bacteriophage ◽  
Complete Genomic

scholarly journals Different Classes of Antibiotics Differentially Influence Shiga Toxin Production

2010 ◽  
Vol 54 (9) ◽  
pp. 3790-3798 ◽  
Author(s):  
Colleen Marie McGannon ◽  
Cynthia Ann Fuller ◽  
Alison Ann Weiss
Keyword(s):  
Shiga Toxin ◽  
Vero Cells ◽  
Toxin Production ◽  
Lytic Cycle ◽  
Temperate Bacteriophage ◽  
E Coli ◽  
Growth Inhibitory ◽  
Target Dna ◽  
Stress Signals ◽  
Very High

ABSTRACTShiga toxin (Stx) inEscherichia coliO157:H7 is encoded as a late gene product by temperate bacteriophage integrated into the chromosome. Phage late genes, includingstx, are silent in the lysogenic state. However, stress signals, including some induced by antibiotics, trigger the phage to enter the lytic cycle, and phage replication and Stx production occur concurrently. In addition to the Stx produced by O157:H7, phage produced by O157:H7 can infect harmless intestinalE. coliand recruit them to produce Shiga toxin. To understand how antibiotics influence Stx production, Stx lysogens were treated with different classes of antibiotics in the presence or absence of phage-sensitiveE. coli, and Stx-mediated inhibition of protein synthesis was monitored using luciferase-expressing Vero cells. Growth-inhibitory levels of antibiotics suppressed Stx production. Subinhibitory levels of antibiotics that target DNA synthesis, including ciprofloxacin (CIP) and trimethoprim-sulfamethoxazole, increased Stx production, while antibiotics that target the cell wall, transcription, or translation did not. More Stx was produced whenE. coliO157:H7 was incubated in the presence of phage-sensitiveE. colithan when grown as a pure culture. Remarkably, very high levels of Stx were detected even when growth of O157:H7 was completely suppressed by CIP. In contrast, azithromycin significantly reduced Stx levels even when O157:H7 viability remained high.

scholarly journals Characterization of the genetic switch from phage phi13 important for Staphylococcus aureus colonization in humans

2021 ◽  
Author(s):  
Camilla Kristensen ◽  
Anders Varming ◽  
Helena Leinweber ◽  
Karin Hammer ◽  
Leila Lo Leggio ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Virulence Factors ◽  
Bacterial Genome ◽  
Host Factors ◽  
Human Pathogen ◽  
Switch Region ◽  
Genetic Switch ◽  
Dna Damaging Agents ◽  
Beta Galactosidase

Temperate phages are bacterial viruses that either reside integrated in a bacterial genome as lysogens or enter a lytic lifecycle. Decision between lifestyles is determined by a switch involving a phage-encoded repressor, CI, and a promoter region from which lytic and lysogenic genes are divergently transcribed. Here we investigate the switch of phage phi13 from the human pathogen Staphylococcus aureus. phi13 encodes several virulence factors and is prevalent in S. aureus strains colonizing humans. We show that the phi13 switch harbors a cI gene, a predicted mor (modulator of repression) gene, and three high-affinity operator sites binding CI. To quantify the decision between lytic and lysogenic lifestyle, we introduced reporter plasmids that carry the 1.3 kb switch region from phi13 with the lytic promoter fused to lacZ into S. aureus and B. subtilis. Analysis of beta-galactosidase expression indicated that decision frequency is independent of host factors. The white “lysogenic” phenotype, which relies on expression of cI, could be switched to a stable blue “lytic” phenotype by DNA damaging agents. We have characterized lifestyle decisions of phage phi13, and our approach may be applied to other temperate phages encoding virulence factors in S. aureus.

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