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Updated: Jul 8, 2026

A Fluorescence-based Method to Study Bacterial Gene Regulation in Infected Tissues
Published on: February 19, 2019
LuxS and expression of virulence factors in Streptococcus intermedius
D Pecharki1, F C Petersen, A Aa Scheie
1Department of Oral Biology, Faculty of Dentistry, University of Oslo, Oslo, Norway. ddasilva@odont.uio.no
Background/Aims:
Autoinducer-2 (AI-2) is used by several bacteria in quorum-sensing signaling and is a product of LuxS. The aim was to investigate the effect of LuxS mutation on expression of Streptococcus intermedius virulence factors.
Methods:
S. intermedius mutants were constructed by insertion inactivation or gene deletion. Real time RT-PCR was used to assess transcription of pas, ily and hyl. Hyaluronidase and intermedilysin activities were measured biochemically.
Results:
The results indicated that disruption of luxS in S. intermedius may affect hyaluronidase and intermedilysin gene expressions. No difference in antigen I/II expression was observed. Biochemical methods showed a five-fold decrease in hemolytic activity of the luxS mutant; however, secreted hyaluronidase activity was unaffected. The AI-2 precursor 4,5-dihydroxy-2,3-pentanedione complemented lack of AI-2 production by the mutant thus restoring hemolytic activity.
Conclusions:
We suggest that AI-2 communication is involved in intermedilysin expression.
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