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Mini-Mu-duction as a test for genetic complementation in Escherichia coli
Abstract:
In mini-Mu-duction, segments of host DNA bracketed between two copies of an internally deleted Mu phage (a mini-Mu) can be packaged within Mu phage particles. Upon infection of a second host strain, the DNA injected by these particles can insert into the chromosomal DNA in a reaction catalyzed by the phage A gene product (transposase), which is independent of homologous recombination. This results in a partially diploid host strain in which the duplicated host DNA is bracketed by two copies of the mini-Mu phage (Faelen et al., Mol. Gen. Genet. 176:191-197, 1979). The frequency of mini-Mu-duction reported previously was low (10(-8) to 10(-9) per recipient cell) thus limiting its use to rather stable mutational lesions. I have increased the frequency of mini-Mu-duction 10- to 100-fold by use of a helper phage lacking the kil gene and by UV irradiation of the phage stocks. I have also shown that mini-Mu-duction is a reliable complementation assay in rec+ as well as recA recipient strains. This genetic complementation test does not require prior gene localization and (due to the extended host range of phage Mu) should be applicable to many enterobacterial species.
Insights
Researchers enhanced mini-Mu-duction frequency 10- to 100-fold, enabling its use as a reliable genetic complementation assay for various enterobacterial species.
Area of Science:
- Microbiology
- Molecular Biology
- Bacteriology
Background:
- Mini-Mu-duction facilitates host DNA transfer via Mu phage particles.
- Previous low frequencies limited its application to stable mutations.
Purpose of the Study:
- To significantly increase mini-Mu-duction efficiency.
- To establish mini-Mu-duction as a robust genetic complementation assay.
Main Methods:
- Utilized a helper phage lacking the kil gene.
- Employed UV irradiation of phage stocks.
- Tested complementation in rec+ and recA recipient strains.
Main Results:
- Achieved a 10- to 100-fold increase in mini-Mu-duction frequency.
- Demonstrated mini-Mu-duction's reliability as a complementation assay.
- Confirmed applicability across different recipient strains.
Conclusions:
- Enhanced mini-Mu-duction overcomes previous frequency limitations.
- This method serves as a versatile genetic complementation tool.
- Its broad host range makes it applicable to diverse enterobacteria.
