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Updated: Aug 14, 2026
Generation of a Gene-disrupted Streptococcus mutans Strain Without Gene Cloning
Published on: October 23, 2017
Identification of genes associated with mutacin I production in Streptococcus mutans using random insertional
Phoebe Tsang1, Justin Merritt2, Trang Nguyen1
1UCLA School of Dentistry, Los Angeles, CA 90025, USA.
Abstract:
Streptococcus mutans is a major pathogen implicated in dental caries. Its virulence is enhanced by its ability to produce bacteriocins, called mutacins, which inhibit the growth of other Gram-positive bacteria. The goal of this study is to use a random insertional mutagenesis approach to search for genes that are associated with mutacin I production in the virulent strain UA140. A random insertional mutagenesis library consisting of 11,000 clones was constructed and screened for a mutacin-defective phenotype. Mutacin-defective clones were isolated, and their insertion sites were determined by PCR amplification or plasmid rescue followed by sequencing. A total of twenty-five unique genes were identified. These genes can be categorized into the following functional classes: two-component sensory systems, stress responses, energy metabolism and central cellular processes. Several conserved hypothetical proteins with unknown functions were also identified. These results suggest that mutacin I production is stringently controlled by diverse and complex regulatory pathways.
Insights
Researchers identified 25 genes controlling mutacin I production in Streptococcus mutans, a key bacterium in dental caries. This finding reveals complex regulatory pathways governing virulence factor expression.
Area of Science:
- Microbiology
- Genetics
- Oral Health
Background:
- Streptococcus mutans is a primary cause of dental caries.
- Mutacins, bacteriocins produced by S. mutans, enhance its virulence by inhibiting competing Gram-positive bacteria.
- Understanding mutacin production is crucial for developing strategies against dental caries.
Purpose of the Study:
- To identify genes involved in mutacin I production in the virulent S. mutans strain UA140.
- To utilize random insertional mutagenesis for discovering novel regulatory genes.
- To elucidate the genetic basis of mutacin I biosynthesis and regulation.
Main Methods:
- Construction and screening of an 11,000-clone random insertional mutagenesis library.
- Isolation and characterization of mutacin-defective mutants.
- Determination of gene insertion sites using PCR amplification and plasmid rescue followed by sequencing.
Main Results:
- Identification of twenty-five unique genes associated with mutacin I production.
- Categorization of identified genes into functional classes: two-component sensory systems, stress responses, energy metabolism, and central cellular processes.
- Discovery of several conserved hypothetical proteins with previously unknown functions.
Conclusions:
- Mutacin I production in Streptococcus mutans is regulated by a diverse and complex network of genes.
- The identified genes provide new targets for understanding and potentially controlling dental caries pathogenesis.
- Further research into these regulatory pathways can lead to novel therapeutic interventions.
