scholarly journals Transduction of Low-Copy Number Plasmids by Bacteriophage P22

Genetics ◽  
1997 ◽  
Vol 146 (2) ◽  
pp. 447-456 ◽  
Author(s):  
Brandon A Mann ◽  
James M Slauch
Keyword(s):  
Copy Number ◽  
Rolling Circle Replication ◽  
Bacteriophage P22 ◽  
Genome Packaging ◽  
Rolling Circle ◽  
Size Dependent ◽  
Recombination Proteins ◽  
Low Copy Number ◽  
Dependent Mechanism

The generalized transducing bacteriophage of Salmonella typhimurium, P22, can transduce plasmids in addition to chromosomal markers. Previous studies have concentrated on transduction of pBR322 by P22 and P22HT, the high transducing mutant of P22. This study investigates the mechanism of P22HT transduction of low-copy number plasmids, namely pSC101 derivatives. We show that P22HT transduces pSC101 derivatives that share homology with the chromosome by two distinct mechanisms. In the first mechanism, the plasmid integrates into the chromosome of the donor by homologous recombination. This chromosomal fragment is then packaged in the transducing particle. The second mechanism is a size-dependent mechanism involving a putative plasmid multimer. We propose that this multimer is formed by interplasmidic recombination. In contrast, P22HT can efficiently transduce pBR322 by a third mechanism, which is independent of plasmid homology with the chromosome. It has been proposed that the phage packages a linear concatemer created during rolling circle replication of pBR322, similar in fashion to phage genome packaging. This study investigates the role of RecA, RecD, and RecF recombination proteins in plasmid/plasmid and plasmid/chromosome interactions that form packageable substrates in the donor. We also examine the resolution of various transduced plasmid species in the recipient and the roles of RecA and RecD in these processes.

scholarly journals A phage parasite deploys a nicking nuclease effector to inhibit replication of its viral host

2021 ◽  
Author(s):  
Kristen LeGault ◽  
Zachary Barth ◽  
Peter DePaola ◽  
Kimberley Seed
Keyword(s):  
Genome Replication ◽  
Cleavage Sites ◽  
Structural Components ◽  
Rolling Circle Replication ◽  
Progeny Production ◽  
Unknown Mechanism ◽  
Rolling Circle ◽  
Putative Phage

PLEs are phage parasites integrated into the chromosome of epidemic Vibrio cholerae. In response to infection by its viral host ICP1, PLE excises, replicates and hijacks ICP1 structural components for transduction. Through an unknown mechanism PLE prevents ICP1 from transitioning to rolling circle replication (RCR), a prerequisite for efficient packaging of the viral genome. Here, we characterize a PLE-encoded nuclease, NixI, that blocks phage development likely by nicking ICP1s genome as it transitions to RCR. NixI-dependent cleavage sites appear in ICP1s genome during infection of PLE(+) V. cholerae. Purified NixI demonstrates in vitro specificity for sites in ICP1s genome and NixI activity is enhanced by a putative specificity determinant co-expressed with NixI during phage infection. Importantly, NixI is sufficient to limit ICP1 genome replication and eliminate progeny production. We identify distant NixI homologs in an expanded family of putative phage satellites in Vibrios that lack nucleotide homology to PLEs but nonetheless share genomic synteny with PLEs. More generally, our results reveal a previously unknown mechanism deployed by phage parasites to limit packaging of their viral hosts genome and highlight the prominent role of nuclease effectors as weapons in the arms race between antagonizing genomes.

scholarly journals A Plasmid Isolated from Phytopathogenic Onion Yellows Phytoplasma and Its Heterogeneity in the Pathogenic Phytoplasma Mutant

1998 ◽  
Vol 11 (11) ◽  
pp. 1031-1037 ◽  
Author(s):  
Tsutomu Kuboyama ◽  
Chieh-Chen Huang ◽  
Xiaoyun Lu ◽  
Toshimi Sawayanagi ◽  
Tokiko Kanazawa ◽  
...  
Keyword(s):  
Copy Number ◽  
Open Reading Frame ◽  
Extrachromosomal Dna ◽  
Rolling Circle Replication ◽  
Banding Patterns ◽  
Rolling Circle ◽  
Rep Protein ◽  
Reading Frame ◽  
Dna And Rna ◽  
Dna Fragment

A 3.6-kbp DNA fragment was cloned from the extrachromosomal DNA of a pathogenic plant mollicute, onion yellows phytoplasma (OY-W). Sequence analysis of the fragment revealed an open reading frame (ORF) encoding the replication (Rep) protein of rolling-circle replication (RCR)-type plasmids. This result suggests the existence of a plasmid (pOYW1) in OY-W that uses the RCR mechanism. This assumption was confirmed by detecting the single-stranded DNA (ssDNA) of a replication intermediate that is specifically produced by the RCR mechanism. This is the first report on the identification of the replication system of this plasmid and the genes encoded in it. With a DNA fragment including the Rep gene region of pOYW1 used as a probe, Southern and Northern (RNA) blot hybridizations were employed to examine the heterogeneity between the plasmids found in OY-W and a pathogenic mutant (OY-M) isolated from OY-W. Multiple bands were detected in the DNA and RNA extracted from both OY-W and OY-M infected plants, although the banding patterns were different. Moreover, the copy number of plasmids from OY-W was about 4.2 times greater than that from OY-M. These results indicate constructive heterogeneity between OY-W and OY-M plasmids, and the possibility of a relationship between the plasmid-encoded genes and the pathogenicity of the phytoplasma was suggested.

scholarly journals Role of Individual Monomers of a Dimeric Initiator Protein in the Initiation and Termination of Plasmid Rolling Circle Replication

2000 ◽  
Vol 275 (18) ◽  
pp. 13529-13534 ◽  
Author(s):  
Tseh-Ling Chang ◽  
M. Gabriela Kramer ◽  
Rais A. Ansari ◽  
Saleem A. Khan
Keyword(s):  
Rolling Circle Replication ◽  
Rolling Circle ◽  
Initiator Protein

AR Copy Number and AR Signaling-directed Therapies in Castrationresistant Prostate Cancer

2018 ◽  
Vol 18 (9) ◽  
pp. 869-876
Author(s):  
Samanta Salvi ◽  
Vincenza Conteduca ◽  
Cristian Lolli ◽  
Sara Testoni ◽  
Valentina Casadio ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Copy Number ◽  
Clinical Trial Design ◽  
Complete Information ◽  
Castration Resistant Prostate Cancer ◽  
Castration Resistant ◽  
Anti Cancer ◽  
Hormone Sensitive ◽  
Predictive And Prognostic Biomarker

Background: Adaptive upregulation of Androgen Receptor (AR) is the most common event involved in the progression from hormone sensitive to Castration-Resistant Prostate Cancer (CRPC). AR signaling remains the main target of new AR signalling-directed therapies such as abiraterone and enzalutamide in CRPC patients. Objective: In this review, we discuss general mechanisms of resistance to AR-targeted therapies, with a focus on the role of AR Copy Number (CN). We reported methods and clinical applications of AR CN evaluation in tissue and liquid biopsy, thus to have a complete information regarding its role as predictive and prognostic biomarker. Conclusion: Outcomes of CRPC patients are reported to be highly variable as the consequence of tumor heterogeneity. AR CN could contribute to patient selection and tumor monitoring in CRPC treated with new anti-cancer treatment as abiraterone and enzalutamide. Further studies to investigate AR CN effect to these agents and its potential combination with other prognostic or predictive clinical factors are necessary in the context of harmonized clinical trial design.

The role of rough surface in the size-dependent behavior upon nano-indentation

2021 ◽  
pp. 103836
Author(s):  
Ding Tang ◽  
Leilei Zhao ◽  
Huamiao Wang ◽  
Dayong Li ◽  
Yinghong Peng ◽  
...  
Keyword(s):  
Rough Surface ◽  
Nano Indentation ◽  
Size Dependent ◽  
Dependent Behavior
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