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Global changes in gene expression in Escherichia coli K12 induced by bacteriophage Mu Gem protein
R H Butler1, P Ghelardini, D Fruci
1Istituto di Biologia Cellulare, Consiglio Nazionale delle Ricerche, Rome.
Abstract:
We have studied the growth properties of some Mu lysogens with respect to the non-lysogenic strain and have observed that the division time in minimal medium was increased over 4-fold when the bacteria carried the prophage mutated in the gem gene (Mu gem3). Since this phage gene has previously been shown to be involved in modulation of expression of host genes, we have analysed the proteins extracted from lysogens and non-lysogens as a rapid assay of global gene expression. The pattern of proteins extracted showed marked quantitative variations between non-lysogens, lysogens for wild-type Mu and lysogens for phage Mu gem3. These effects were no longer as evident when the strains were grown in rich medium. This dramatic change in the physiological state of the lysogenic strain versus the non-lysogenic in particular growth conditions extends the concept of lysogeny. For many years, the prophage has been considered only as a potentially lethal factor, while here it also appears as a genetic element capable of profoundly modifying host biology.
Insights
Bacteriophage Mu gem3 significantly slows bacterial growth and alters protein expression in minimal media. This highlights the prophage as a key genetic element influencing host biology beyond its lethal potential.
Area of Science:
- Microbiology
- Molecular Biology
- Bacteriology
Background:
- Bacteriophage Mu is a well-studied temperate phage.
- The Mu gem gene is known to modulate host gene expression.
- Lysogeny, the state where phage DNA integrates into the host genome, has been primarily viewed as a potentially lethal factor.
Purpose of the Study:
- To investigate the impact of bacteriophage Mu lysogeny on bacterial growth properties.
- To analyze global gene expression changes in bacteria lysogenized with wild-type Mu and a mutated gem gene (Mu gem3).
- To extend the understanding of lysogeny's role in host biology.
Main Methods:
- Comparative growth studies of non-lysogenic bacteria, wild-type Mu lysogens, and Mu gem3 lysogens in minimal medium.
- Analysis of protein expression patterns using protein extraction from lysogenic and non-lysogenic bacterial strains.
- Assessment of gene expression under different growth conditions (minimal vs. rich medium).
Main Results:
- Lysogeny with Mu gem3 resulted in a greater than 4-fold increase in bacterial division time in minimal medium compared to non-lysogenic strains.
- Significant quantitative variations in protein expression patterns were observed between non-lysogens, wild-type Mu lysogens, and Mu gem3 lysogens.
- These pronounced physiological effects were diminished when bacteria were grown in rich medium.
Conclusions:
- The Mu gem gene plays a crucial role in modulating bacterial physiology during lysogeny.
- Bacteriophage prophages can act as genetic elements profoundly altering host biology, extending the concept of lysogeny beyond a mere potentially lethal factor.
- Environmental conditions, such as nutrient availability (minimal vs. rich medium), significantly influence the manifestation of phage-induced host modifications.