Background and objective: The stress-response mechanism in Treponema denticola, one of the major periodontal pathogens, has yet to be elucidated. Previously, we found that the expression of a potential transcriptional regulator was significantly increased in the T. denticola mutant deficient in major outer sheath protein (Msp). Because loss of Msp may cause stress on outer sheath of T. denticola, we hypothesized that the gene might be involved in the stress response. Therefore, we focused on an operon including the potential transcriptional regulator. The aim of this study is to elucidate the part of stress-response mechanism in T. denticola, through analyzing the function of this operon. Materials and
Methods: We constructed two mutant strains deficient in each gene located in the operon from T. denticola ATCC35405 (wild-type strain). The gene-expression profiles of the mutants were analyzed by DNA microarray and qRT-PCR. Based on the results of the genetic analyses, we investigated some phenotypic changes of the mutants.
Results: In the genetic analyses, we observed the differential expression of the genes involved in the motility of T. denticola. The mutant deficient in the potential transcriptional regulator showed no change in growth, while that of the mutant deficient in the downstream gene was attenuated. Furthermore, the motility of both mutant strains was significantly decreased compared with that of wild-type strain.
Conclusion: The target genes in the operon might be involved in the response against the stress on outer sheath of T. denticola, through regulating the motility of this bacterium.
