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Transcription of bacteriophage Mu. II. Transcription of the repressor gene
Abstract:
Using pBR322 as a vector, three plasmids were constructed, pGP2, pGP3, and pGP7, containing respectively 5, 100, 700-950, and 1,000 base pairs derived from the immunity end of bacteriophage Mu. All three plasmids contain a functional repressor gene coding for a thermosensitive repressor. RNAs produced when the DNA of these plasmids was used as template in in vitro RNA synthesis, were analysed by hybridization to the DNA of several lambda pMu transducing phages. In spite of the differences in length of the Mu fragments all three plasmids show the same amount of Mu specific l-strand transcription. Since the repressor gene comprises at least 70% of the Mu fragments of pGP3 and pGP7, these results indicate that the repressor gene c of bacteriophage Mu is transcribed on the l-strand. Analysis of in vivo RNA from cells harboring the plasmids pGP2, pGP3, or pGP7 also indicates that the repressor gene of phage Mu is transcribed on the l-strand, as all Mu-specific RNA extracted from these cells at 28 degrees C hybridizes with the l-strand of the first 3,100 basepairs from the Mu immunity end.
Insights
Researchers investigated bacteriophage Mu gene transcription using constructed plasmids. Results indicate the bacteriophage Mu repressor gene (c) is transcribed on the l-strand, confirmed by both in vitro and in vivo RNA analysis.
Area of Science:
- Molecular Biology
- Virology
- Genetics
Background:
- Bacteriophage Mu is a temperate bacteriophage with a complex genome structure.
- Understanding bacteriophage gene regulation is crucial for viral replication and host interaction studies.
- The immunity region of bacteriophage Mu contains essential regulatory genes, including the repressor gene c.
Purpose of the Study:
- To determine the transcriptional orientation of the bacteriophage Mu repressor gene (c).
- To analyze Mu-specific RNA transcription from constructed plasmids in vitro and in vivo.
- To confirm the strand on which the bacteriophage Mu repressor gene is transcribed.
Main Methods:
- Construction of three plasmids (pGP2, pGP3, pGP7) containing varying lengths of the bacteriophage Mu immunity region using pBR322 as a vector.
- In vitro RNA synthesis using plasmid DNA as a template.
- RNA-DNA hybridization analysis using lambda pMu transducing phages to quantify Mu-specific transcription.
- Analysis of in vivo RNA extracted from bacterial cells harboring the constructed plasmids.
Main Results:
- All three plasmids demonstrated consistent levels of Mu-specific l-strand transcription, irrespective of fragment length.
- The bacteriophage Mu repressor gene (c) constitutes a significant portion (≥70%) of the Mu fragments in pGP3 and pGP7.
- Both in vitro and in vivo RNA analyses confirmed that Mu-specific RNA hybridizes with the l-strand of the Mu immunity region, indicating transcription on the l-strand.
Conclusions:
- The bacteriophage Mu repressor gene (c) is transcribed on the l-strand.
- This finding clarifies the transcriptional direction of a key regulatory gene in bacteriophage Mu.
- The study provides foundational data for further investigations into bacteriophage Mu gene expression and regulation.