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Updated: Oct 29, 2025
Purification of a High Molecular Mass Protein in Streptococcus mutans
Published on: September 14, 2019
[Association of sepM gene mutation with mutacin Ⅳ production by Streptococcus mutans]
1Department of Stomatology, First Affiliated Hospital of Bengbu Medical College, Bengbu 233004, China.
Objective:
To investigate the types of sepM gene mutations and their distribution in clinical isolates of Streptococcus mutans (S. mutans) and explore the association of sepM gene mutation with the capacity of mutacin Ⅳ production by S. mutans.
Objective:
We assessed the capacity of mutacin Ⅳ production in 80 clinical isolates of S. mutans using an inhibition zone assay. The minimum spanning tree and phylogenetic tree of these isolates were constructed using core genome multilocus sequence typing and maximum likelihood method, respectively. GeneMarkS software was used to predict the coding genes of these isolates, and the predicted genes were blasted against the sepM gene sequence of the reference genome UA159 to determine sepM gene mutations and their distribution characteristics in the clinical isolates. The mutation types affecting mutacin Ⅳ production were identified by analyzing the differentially distributed mutations between mutacin Ⅳ-producing isolates and mutacin Ⅳ-free isolates and by comparing the inhibition zones between isolates with sepM gene mutations and those without mutations.
Objective:
Among the 80 clinical isolates of S. mutans, 25 isolates were capable of mutacin Ⅳ production and 55 did not produce mutacin Ⅳ. The minimum spanning tree showed that the allelic differences were less among the mutacin Ⅳproducing isolates than among the mutacin Ⅳ-free isolates, and the origins of the mutacin Ⅳ-producing isolates were similar. We identified a total of 34 single base mutations in the 80 clinical isolates, and among them, C31T (P=0.001), G533A (P < 0.001), C756T (P=0.025), and C1036T (P=0.003) showed significant differential distributions between the mutacin Ⅳ-producing and mutacin Ⅳ-free isolates. These differentially distributed mutations were positively correlated with the capacity of mutacin Ⅳ production of the bacteria.
Objective:
sepM gene mutations that affect the capacity of mutacin Ⅳ production are present in the clinical strains of S. mutans.
Insights
Specific mutations in the Streptococcus mutans (S. mutans) sepM gene are linked to the bacteria's ability to produce mutacin IV. These findings highlight genetic factors influencing S. mutans virulence.
Area of Science:
- Microbiology
- Genetics
- Molecular Biology
Background:
- Streptococcus mutans (S. mutans) is a primary agent of dental caries.
- Mutacin IV is a bacteriocin produced by S. mutans that plays a role in its ecological niche and virulence.
- The sepM gene's role in mutacin IV production is not fully understood.
Purpose of the Study:
- To identify and characterize mutations in the sepM gene of clinical S. mutans isolates.
- To investigate the distribution of these sepM gene mutations.
- To determine the association between sepM gene mutations and mutacin IV production capacity.
Main Methods:
- Assessed mutacin IV production in 80 S. mutans clinical isolates using inhibition zone assays.
- Employed core genome multilocus sequence typing and phylogenetic analysis for isolate characterization.
- Utilized GeneMarkS and BLAST analysis to identify sepM gene mutations and their distribution.
Main Results:
- 25 out of 80 isolates produced mutacin IV; 55 did not.
- Identified 34 single base mutations in the sepM gene across isolates.
- Four specific mutations (C31T, G533A, C756T, C1036T) were significantly associated with mutacin IV production (P<0.001–0.025).
Conclusions:
- Specific sepM gene mutations are present in clinical S. mutans strains.
- These identified mutations are positively correlated with the capacity for mutacin IV production.
- Genetic variations in sepM influence the virulence factor production in S. mutans.
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