Project description:To understand the role of CdhR and its adjacent gene PG1236 in nitric oxide (NO) stress resistance, isogenic mutants P. gingivalis FLL457 (ΔPG1237::ermF), FLL458 (ΔPG1236::ermF) and FLL459 (ΔPG1236-37::ermF) were made by allelic exchange mutagenesis and their gene expression was studied under control and NO stress conditions. DNA microarray analysis of FLL457 showed that approximately 2% of the genes were up regulated and over 1% of the genes down regulated. Transcriptome analysis of FLL458 and FLL459 under NO stress showed similar modulation patterns in both mutants for a few genes. The PG1236-7 gene cluster seemed to be part of the same transcriptional unit that showed increased expression under NO stress. Recombinant CdhR showed binding activity to the predicted promoter regions of PG1459 and PG0495.
Project description:To understand the role of CdhR and its adjacent gene PG1236 in nitric oxide (NO) stress resistance, isogenic mutants P. gingivalis FLL457 (ΔPG1237::ermF), FLL458 (ΔPG1236::ermF) and FLL459 (ΔPG1236-37::ermF) were made by allelic exchange mutagenesis and their gene expression was studied under control and NO stress conditions. DNA microarray analysis of FLL457 showed that approximately 2% of the genes were up regulated and over 1% of the genes down regulated. Transcriptome analysis of FLL458 and FLL459 under NO stress showed similar modulation patterns in both mutants for a few genes. The PG1236-7 gene cluster seemed to be part of the same transcriptional unit that showed increased expression under NO stress. Recombinant CdhR showed binding activity to the predicted promoter regions of PG1459 and PG0495. Taken together, the data indicate that CdhR may play a role in NO stress resistance and be involved in a regulatory network in P. gingivalis.
Project description:To survive in the periodontal pocket, Porphyromonas gingivalis, the main causative agent of periodontal disease, must overcome oxidative and nitric oxide (NO) stress. Previously, we reported that, in the presence of NO comparable to stress conditions, the transcriptome of P. gingivalis was differentially expressed, and genes belonging to the PG1178-81 cluster were significantly upregulated. To further evaluate their role(s) in NO stress resistance, these genes were inactivated by allelic exchange mutagenesis. Isogenic mutants P. gingivalis FLL460 (ΔPG1181::ermF) and FLL461 (ΔPG1178-81::ermF) were black-pigmented, with gingipain and hemolytic activities comparable to that of the wild-type strain. Whereas the recovery of these isogenic mutants from NO stress was comparable to the wild-type, there was increased sensitivity to hydrogen peroxide-induced stress. RNA-Seq analysis under conditions of NO stress showed that approximately 5 and 8% of the genome was modulated in P. gingivalis FLL460 and FLL461, respectively. The PG1178-81 gene cluster was shown to be part of the same transcriptional unit and is inducible in response to NO stress. In the presence of NO, PG1181, a putative transcriptional regulator, was shown to bind to its own promoter region and that of several other NO responsive genes including PG0214 an extracytoplasmic function σ factor, PG0893 and PG1236. Taken together, the data suggest that PG1181 is a NO responsive transcriptional regulator that may play an important role in the NO stress resistance regulatory network in P. gingivalis.
Project description:Porphyromonas gingivalis, the causative agent of adult periodontitis, must maintain nitric oxide (NO) homeostasis and surmount nitric oxide stress from host immune responses or other oral bacteria to survive in the periodontal pocket. To determine the involvement of a putative hydroxylamine reductase (PG0893) and a putative nitrite reductase-related protein (PG2213) in P. gingivalis W83 NO stress resistance, genes encoding those proteins were inactivated by allelic exchange mutagenesis. The isogenic mutants P. gingivalis FLL455 (PG0893ermF) and FLL456 (PG2213ermF) were black pigmented and showed growth rates and gingipain and hemolytic activities similar to those of the wild-type strain. P. gingivalis FLL455 was more sensitive to NO than the wild type. Complementation of P. gingivalis FLL455 with the wild-type gene restored the level of NO sensitivity to a level similar to that of the parent strain. P. gingivalis FLL455 and FLL456 showed sensitivity to oxidative stress similar to that of the wild-type strain. DNA microarray analysis showed that PG0893 and PG2213 were upregulated 1.4- and 2-fold, respectively, in cells exposed to NO. In addition, 178 genes were upregulated and 201 genes downregulated more than 2-fold. The majority of these modulated genes were hypothetical or of unknown function. PG1181, predicted to encode a transcriptional regulator, was upregulated 76-fold. Transcriptome in silico analysis of the microarray data showed major metabolomic variations in key pathways. Collectively, these findings indicate that PG0893 and several other genes may play an important role in P. gingivalis NO stress resistance.