ECF sigma factors in adaptation and virulence of Porphyromonas gingivalis

描述（申请人提供）：牙龈卟啉单胞菌是牙周病的重要病原体。牙周袋的恶劣炎症条件，加上感染和定植过程中遇到的环境变化，表明这种生物体具有促进其响应和适应压力的能力的特性。病原体的应激反应是其毒力的主要决定因素。一般来说，已知的反应和适应机制主要在转录起始水平由胞质外功能（extracytoplasmic function， ECF） sigma因子调节，这是最大的可选sigma因子组。迄今为止，关于牙龈卟啉卟啉的适应性机制、毒力调节和ECF sigma因子之间的关系知之甚少。由于宿主内的恶劣环境可能会影响入侵细菌的膜结构，因此我们的假设是，在牙龈卟啉卟啉菌中，ECF¿因子协调调节对细菌生长至关重要的机制

DESCRIPTION (provided by applicant): Porphyromonas gingivalis is an important etiologic agent of periodontal disease. The harsh inflammatory conditions of the periodontal pocket, in addition to the environmental changes encountered during infection and colonization, suggest that this organism has properties that will facilitate its ability to respond and adapt to stress. Stress response in the pathogen is a major determinant of its virulence. In general, the response and adaptation mechanisms are known to be mostly regulated at the level of transcription initiation by extracytoplasmic function (ECF) sigma factor, the largest group of alternative sigma factors. To date, little is known about the relationship between the regulation of adaptive mechanisms, virulence, and ECF sigma factors in P. gingivalis. Because the hostile environment within the host will likely affect the membrane architecture of the invading bacteria, it is our hypothesis that in P. gingivalis ECF ¿ factors coordinately regulate mechanisms vital for protection against environmental stress and are significant in the pathogenicity of the organism. In the genome of Porphyromonas gingivalis W83, six putative ECF ¿ factors were identified. In preliminary studies, we have inactivated five ECF ¿ factor genes (PG0162, PG0214, PG0985, PG1660, and PG1827) by allelic exchange mutagenesis. Taken together, our findings suggest that in P. gingivalis ECF sigma factors can modulate important virulence factors. ECF ¿ factors encoded by the PG0162 and PG1660 genes might also be involved in the post-transcriptional regulation of the gingipains. Bioinformatics analysis suggests that PG0162 and PG1660 are paralogs that have unique properties. It is likely that they may be involved in unique and complex regulatory mechanisms. In this project, we wish to gain a comprehensive understanding of P. gingivalis ECF ¿ factors and their role in an adaptive response to the environmental conditions typical of the periodontal pocket. The Specific Aims are: (1) To confirm and characterize the properties of specific ECF sigma factors in P. gingivalis. (2) To identify the environmental stress signals and sensor protein(s) involved in the modulation of PG1660. (3) To identify the genes in the PG1660 regulon(s) and characterize the regulatory sequences involved in the expression of those genes. Collectively, the data generated will facilitate a comprehensive assessment of the role of ECF ¿ factors in regulating gene expression, identifying pathways of adaptation to environmental stress typical of the periodontal pocket and evaluating their impact on pathogenicity of P. gingivalis. Because many of the proteins in this study are unique, drugs designed to inhibit these targets could be an attractive therapeutic strategy to aid in the prevention of P. gingivalis-associated diseases.