Himar1 Transposon for Efficient Random Mutagenesis in Aggregatibacter actinomycetemcomitans

Area of Science:

• Microbiology
• Genetics
• Periodontology

Background:

• Aggregatibacter actinomycetemcomitans is the primary cause of aggressive periodontal disease.
• Efficient genetic tools for genome-wide mutagenesis are lacking in A. actinomycetemcomitans, hindering virulence factor identification.

Purpose of the Study:

• To evaluate the utility of the Himar1 mariner transposon system for genetic analysis in A. actinomycetemcomitans.
• To develop a high-throughput screening method for identifying A. actinomycetemcomitans mutants with altered biofilm formation.

Main Methods:

• Himar1 transposon mutagenesis was performed on wild-type A. actinomycetemcomitans strains (serotypes a, b, and c).
• A library of 16,000 A. actinomycetemcomitans mutants was generated and screened for reduced biofilm formation.
• Transposon insertion stability and frequency were assessed.

Main Results:

• Himar1 mutagenesis occurred at a high frequency (10^-4) and was applicable to multiple A. actinomycetemcomitans serotypes.
• Transposon insertions were stably inherited in the absence of antibiotics.
• Mutants with insertions in genes related to pili, ion transport, multidrug resistance, transcription regulation, EPS synthesis, metabolism, and stress response were identified.

Conclusions:

• The Himar1 transposon system is a valuable and efficient genetic tool for functional genomic analysis in A. actinomycetemcomitans.
• This system facilitates the discovery of novel virulence factors and genes involved in biofilm formation.
• The developed mutagenesis and screening approach can be applied to other bacterial species.