scholarly journals Bacteriophage λ RexA and RexB Functions Assist the Transition from Lysogeny to Lytic Growth

2021 ◽  
Author(s):  
Lynn C. Thomason ◽  
Carl J. Schiltz ◽  
Carolyn Court ◽  
Christopher J. Hosford ◽  
Myfanwy C. Adams ◽  
...  
Keyword(s):  
Dna Replication ◽  
Reporter Genes ◽  
Bacteriophage Λ ◽  
Bistable Switch ◽  
Immune State ◽  
Phage Dna ◽  
Cro Repressor ◽  
Repressor Synthesis ◽  
Stable Maintenance

SummaryThe CI and Cro repressors of bacteriophage λ create a bistable switch between lysogenic and lytic growth. In λ lysogens, CI repressor expressed from thePRMpromoter blocks expression of the lytic promotersPLandPRto allow stable maintenance of the lysogenic state. When lysogens are induced, CI repressor is inactivated and Cro repressor is expressed from the lyticPRpromoter. Cro repressor blocksPRMtranscription and CI repressor synthesis to ensure that the lytic state proceeds. RexA and RexB proteins, like CI, are expressed from thePRMpromoter in λ lysogens; RexB is also expressed from a second promoter,PLIT, embedded inrexA.Here we show that RexA binds CI repressor and assists the transition from lysogenic to lytic growth, using both intact lysogens and defective prophages with reporter genes under control of the lyticPLandPRpromoters. Once lytic growth begins, if the bistable switch does return to the immune state, RexA expression lessens the probability that it will remain there, thus stabilizing the lytic state and activation of the lyticPLandPRpromoters. RexB modulates the effect of RexA and may also help establish phage DNA replication as lytic growth ensues.

Replication of Bacteriophage 186 DNA

1972 ◽  
Vol 30 ◽  
pp. 194-195
Author(s):  
Dhruba K. Chattoraj ◽  
Ross B. Inman
Keyword(s):  
Electron Microscopy ◽  
Dna Replication ◽  
Frame Of Reference ◽  
Dna Molecules ◽  
E Coli ◽  
Phage Dna ◽  
Partial Denaturation

Electron microscopy of replicating intermediates has been quite useful in understanding the mechanism of DNA replication in DNA molecules of bacteriophage, mitochondria and plasmids. The use of partial denaturation mapping has made the tool more powerful by providing a frame of reference by which the position of the replicating forks in bacteriophage DNA can be determined on the circular replicating molecules. This provided an easy means to find the origin and direction of replication in λ and P2 phage DNA molecules. DNA of temperate E. coli phage 186 was found to have an unique denaturation map and encouraged us to look into its mode of replication.

scholarly journals The Phage φ29 Membrane Protein p16.7, Involved in DNA Replication, Is Required for Efficient Ejection of the Viral Genome

2007 ◽  
Vol 189 (15) ◽  
pp. 5542-5549 ◽  
Author(s):  
Martín Alcorlo ◽  
Víctor González-Huici ◽  
José M. Hermoso ◽  
Wilfried J. J. Meijer ◽  
Margarita Salas
Keyword(s):  
Dna Replication ◽  
Membrane Protein ◽  
Second Step ◽  
Host Proteins ◽  
Viral Dna ◽  
Dna Ejection ◽  
Phage Dna ◽  
Ejection Mechanism ◽  
The Right

ABSTRACT It is becoming clear that in vivo phage DNA ejection is not a mere passive process. In most cases, both phage and host proteins seem to be involved in pulling at least part of the viral DNA inside the cell. The DNA ejection mechanism of Bacillus subtilis bacteriophage φ29 is a two-step process where the linear DNA penetrates the cell with a right-left polarity. In the first step ∼65% of the DNA is pushed into the cell. In the second step, the remaining DNA is actively pulled into the cytoplasm. This step requires protein p17, which is encoded by the right-side early operon that is ejected during the first push step. The membrane protein p16.7, also encoded by the right-side early operon, is known to play an important role in membrane-associated phage DNA replication. In this work we show that, in addition, p16.7 is required for efficient execution of the second pull step of DNA ejection.

scholarly journals UV- and MMS-induced mutagenesis of lambdaO(am)8 phage under nonpermissive conditions for phage DNA replication.

2003 ◽  
Vol 50 (4) ◽  
pp. 921-939 ◽  
Author(s):  
Joanna Krwawicz ◽  
Anna Czajkowska ◽  
Magdalena Felczak ◽  
Irena Pietrzykowska
Keyword(s):  
Dna Replication ◽  
Dna Polymerase ◽  
Excision Repair ◽  
Protein S ◽  
Dna Lesions ◽  
E Coli ◽  
Phage Dna ◽  
Induced Mutagenesis ◽  
C Proteins ◽  
Inducible Protein

Mutagenesis in Escherichia coli, a subject of many years of study is considered to be related to DNA replication. DNA lesions nonrepaired by the error-free nucleotide excision repair (NER), base excision repair (BER) and recombination repair (RR), stop replication at the fork. Reinitiation needs translesion synthesis (TLS) by DNA polymerase V (UmuC), which in the presence of accessory proteins, UmuD', RecA and ssDNA-binding protein (SSB), has an ability to bypass the lesion with high mutagenicity. This enables reinitiation and extension of DNA replication by DNA polymerase III (Pol III). We studied UV- and MMS-induced mutagenesis of lambdaO(am)8 phage in E. coli 594 sup+ host, unable to replicate the phage DNA, as a possible model for mutagenesis induced in nondividing cells (e.g. somatic cells). We show that in E. coli 594 sup+ cells UV- and MMS-induced mutagenesis of lambdaO(am)8 phage may occur. This mutagenic process requires both the UmuD' and C proteins, albeit a high level of UmuD' and low level of UmuC seem to be necessary and sufficient. We compared UV-induced mutagenesis of lambdaO(am)8 in nonpermissive (594 sup+) and permissive (C600 supE) conditions for phage DNA replication. It appeared that while the mutagenesis of lambdaO(am)8 in 594 sup+ requires the UmuD' and C proteins, which can not be replaced by other SOS-inducible protein(s), in C600 supE their functions may be replaced by other inducible protein(s), possibly DNA polymerase IV (DinB). Mutations induced under nonpermissive conditions for phage DNA replication are resistant to mismatch repair (MMR), while among those induced under permissive conditions, only about 40% are resistant.

Involvement of the host initiator function dnaA in the replication of coliphage lambda.

Genetics ◽  
1995 ◽  
Vol 139 (4) ◽  
pp. 1469-1481 ◽  
Author(s):  
G Wegrzyn ◽  
A Wegrzyn ◽  
I Konieczny ◽  
K Bielawski ◽  
G Konopa ◽  
...  
Keyword(s):  
Dna Replication ◽  
High Yield ◽  
Dna Molecules ◽  
Lambda Phage ◽  
Initiation Of Replication ◽  
Phage Dna ◽  
Theta Replication ◽  
Lambdoid Prophage ◽  
Coliphage Lambda ◽  
Lambda Dna

Abstract We demonstrate that the initiation of coliphage lambda DNA replication is dependent on the host initiator function dnaA, provided that the lambdoid prophage Rac is absent. Presence of Rac compensated the absence of dnaA function, causing initiation of replication. In dnaAts rac+ cells at 43 degrees, most of parental phage DNA molecules, after one round of theta replication, switched to a replication with features of the sigma mode and produced progeny at high yield. Initiation of replication of the lambda Pts1 mutant at 43 degrees was blocked by dnaA function; however, under dnaA-rac+ conditions all parental phage DNA molecules, after one round of theta replication, switched to the sigma mode and produced progeny at high yield. Taking into account our recent finding that transcriptional activation of ori lambda seems to be dnaA-regulated (to be published elsewhere), we suggest that the DnaA-lambda Pts1 incompatibility occurs at the insertion of the ori lambda-bound lambda O-lambda P-DnaB preprimosome between the complementary lambda DNA strands. The role of Rac and the mechanism of the switch from theta to sigma mode of lambda phage DNA replication are discussed.

scholarly journals Characterization of the Putative Replisome Organizer of the Lactococcal Bacteriophage r1t

2002 ◽  
Vol 76 (20) ◽  
pp. 10234-10244 ◽  
Author(s):  
Manuel Zúñiga ◽  
Blandine Franke-Fayard ◽  
Gerard Venema ◽  
Jan Kok ◽  
Arjen Nauta
Keyword(s):  
Dna Replication ◽  
Binding Sites ◽  
Direct Repeats ◽  
Dnase I Footprinting ◽  
Phage Dna ◽  
Cognate Gene ◽  
Phage Spp1 ◽  
Dna Strand ◽  
Protection Pattern

ABSTRACT Analysis of the nucleotide sequence of the genome of the lactococcal bacteriophage r1t showed that it may encode at least two proteins involved in DNA replication. On the basis of its similarity with the G38P protein encoded by the Bacillus subtilis phage SPP1, the product of orf11 (Pro11) is thought to be involved in the initiation of phage DNA replication. This protein was overexpressed in Lactococcus lactis and partially purified. Gel retardation analysis using various r1t DNA fragments indicates that Pro11 specifically binds to a sequence located within its cognate gene. DNase I footprinting showed that Pro11 protects a stretch of DNA of 47 bp. This region spans four 6-bp short direct repeats, which suggests that the region contains four binding sites for Pro11. 1,10-Phenanthroline-copper footprinting confirmed the protection of the hexamers. An asymmetric protection pattern of each strand was observed, suggesting that Pro11 contacts each DNA strand separately at contiguous hexamers. We propose a model for the binding of Pro11 to its target sites that may account for the torsion strain required for strand opening at the origin of replication.

Cloning of bacterial DNA replication genes in bacteriophage λ

1982 ◽  
Vol 187 (3) ◽  
pp. 501-509 ◽  
Author(s):  
Lee Rowen ◽  
Joan A. Kobori ◽  
Stewart Scherer
Keyword(s):  
Dna Replication ◽  
Bacteriophage Λ ◽  
Bacterial Dna ◽  
Bacterial Dna Replication
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