Construction of Streptococcus mutans comE Mutant Strain Using In-frame Deletion System / 中国生物工程杂志

ABSTRACT

The intraspecies quorum sensing system of Streptococcus mutans is involved with com genes family.ComE is a kind of response regulator and act as a promoter to the quorum sensing genes.S.mutans comE mutant strain IFD140?comE was constructed using the inframe-deletion system via twice homologous recombination.In current genetic studies of S.mutans,insertion duplication and allelic exchange mutagenesis techniques routinely create polar effects to downstream genes.In-frame deletions are essentially free of these polar effects because the mutation does not introduce any genetic markers.By PCR,sequencing and RT-PCR,it was confirmed that IFD140?comE has only 717bp deleted within the comE gene and the transcription of the downstream gene comD was not interfered.The research of the morphological characteristics indicated that IFD140?comE formed clumps and cells accumulated at the bottom of the glass tubes and light-microscopic observations displayed that the mutant strain formed significantly longer chains compared to those formed by the wild strain.The successfully construction of IFD140?comE lay a foundation for further quorum sensing research.