scholarly journals Elements in the λ immunity region regulate phage development: beyond the ‘Genetic Switch’

2019 ◽  
Vol 112 (6) ◽  
pp. 1798-1813 ◽  
Author(s):  
Lynn C. Thomason ◽  
Kathleen Morrill ◽  
Gillian Murray ◽  
Carolyn Court ◽  
Brenda Shafer ◽  
...  
Keyword(s):  
Genetic Switch ◽  
Immunity Region ◽  
Phage Development

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.

Molecular genetics oftransformer, a genetic switch controlling sexual differentiation inDrosophila

1989 ◽  
Vol 10 (3) ◽  
pp. 143-154 ◽  
Author(s):  
John M. Belote ◽  
Michael McKeown ◽  
Russell T. Boggs ◽  
Risa Ohkawa ◽  
Barbara A. Sosnowski
Keyword(s):  
Molecular Genetics ◽  
Sexual Differentiation ◽  
Genetic Switch

scholarly journals Analysis of the Genetic Switch and Replication Region of a P335-Type Bacteriophage with an Obligate Lytic Lifestyle onLactococcus lactis

2001 ◽  
Vol 67 (3) ◽  
pp. 1128-1139 ◽  
Author(s):  
Søren M. Madsen ◽  
David Mills ◽  
Gordana Djordjevic ◽  
Hans Israelsen ◽  
Todd R. Klaenhammer
Keyword(s):  
Gene Expression ◽  
Attachment Site ◽  
Streptococcus Thermophilus ◽  
Regulatory Elements ◽  
Lytic Phage ◽  
Genetic Switch ◽  
Integrase Gene ◽  
Replication Module ◽  
Gene Homologue ◽  
I Gene

ABSTRACT The DNA sequence of the replication module, part of the lysis module, and remnants of a lysogenic module from the lytic P335 species lactococcal bacteriophage φ31 was determined, and its regulatory elements were investigated. The identification of a characteristic genetic switch including two divergent promoters and two cognate repressor genes strongly indicates that φ31 was derived from a temperate bacteriophage. Regulation of the two early promoters was analyzed by primer extension and transcriptional promoter fusions to a lacLMreporter. The regulatory behavior of the promoter region differed significantly from the genetic responses of temperate Lactococcus lactis phages. Thecro gene homologue regulates its own production and is an efficient repressor of cI gene expression. No detectablecI gene expression could be measured in the presence ofcro. cI gene expression in the absence ofcro exerted minor influences on the regulation of the two promoters within the genetic switch. Homology comparisons revealed a replication module which is most likely expressed from the promoter located upstream of the cro gene homologue. The replication module encoded genes with strong homology to helicases and primases found in several Streptococcus thermophilus phages. Downstream of the primase homologue, an AT-rich noncoding origin region was identified. The characteristics and location of this region and its ability to reduce the efficiency of plaquing of φ31 106-fold when present at high copy number in trans provide evidence for identification of the phage origin of replication. Phage φ31 is an obligately lytic phage that was isolated from commercial dairy fermentation environments. Neither a phage attachment site nor an integrase gene, required to establish lysogeny, was identified, explaining its lytic lifestyle and suggesting its origin from a temperate phage ancestor. Several regions showing extensive DNA and protein homologies to different temperate phages ofLactococcus, Lactobacillus, andStreptococcus were also discovered, indicating the likely exchange of DNA cassettes through horizontal gene transfer in the dynamic ecological environment of dairy fermentations.

The Aspergillus nidulans abaA gene encodes a transcriptional activator that acts as a genetic switch to control development

1994 ◽  
Vol 14 (4) ◽  
pp. 2503-2515
Author(s):  
A Andrianopoulos ◽  
W E Timberlake
Keyword(s):  
Aspergillus Nidulans ◽  
Transcriptional Activation ◽  
Expression System ◽  
Regulatory Gene ◽  
Binding Motif ◽  
Mobility Shift ◽  
Genetic Switch ◽  
Regulatory Regions ◽  
Cis Acting ◽  
Gel Mobility Shift

The Aspergillus nidulans abaA gene encodes a protein containing an ATTS DNA-binding motif and is required for the terminal stages of conidiophore development. Results from gel mobility shift and protection, missing-contact, and interference footprint assays showed that AbaA binds to the sequence 5'-CATTCY-3', where Y is a pyrimidine, making both major- and minor-groove contacts. Multiple AbaA binding sites are present in the cis-acting regulatory regions of several developmentally controlled structural genes as well as those of the upstream regulatory gene brlA, the downstream regulatory gene wetA, and abaA itself. These cis-acting regulatory regions confer AbaA-dependent transcriptional activation in a heterologous Saccharomyces cerevisiae gene expression system. From these observations, we propose that the AbaA transcription factor establishes a novel set of feedback regulatory loops responsible for determination of conidiophore development.

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