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。牙周袋的严酷炎症条件，加上在感染和定居过程中遇到的环境变化，表明这种有机体具有促进其反应和适应压力的能力。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是由胞浆外功能(ECF)西格玛因子在转录启动水平上调节的，西格玛因子是最大的备选西格玛因子组。到目前为止，关于牙龈假单胞菌适应机制的调节、毒力和ECF西格玛因子之间的关系还知之甚少。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，在牙龈假单胞菌中，ECF因子协调调节对 对环境压力的保护，在生物体的致病性方面具有重要意义。在牙龈卟啉单胞菌W83的基因组中，鉴定出6个可能的ECF因子。在初步研究中，我们通过等位基因交换突变使5个ECF因子基因(PG0162、PG0214、PG0985、PG1660和PG1827)失活。综上所述，我们的研究结果表明，在牙龈假单胞菌中，ECF sigma因子可以调节重要的毒力因子。由PG0162和PG1660基因编码的ECF因子也可能参与了牙痛的转录后调节。生物信息学分析表明，PG0162和PG1660是具有独特性质的对偶基因。它们很可能参与了独特而复杂的监管机制。在这个项目中，我们希望全面了解牙龈假单胞菌的ECF因子及其在对牙周袋典型的环境条件做出适应性反应中的作用。其具体目的是：(1)确认和鉴定牙龈假单胞菌中特异性ECF西格玛因子的特性。(2)识别 环境胁迫信号和参与调控PG1660的传感蛋白(S)。(3)鉴定S(PG1660)调控子中的基因，并对这些基因的表达调控序列进行分析。总而言之，产生的数据将有助于全面评估ECF因子在调节基因表达方面的作用，确定适应牙周袋典型环境压力的途径，并评估它们对牙龈假单胞菌致病性的影响。因为这项研究中的许多蛋白质都是独一无二的，所以设计出抑制这些靶点的药物可能是一种有吸引力的治疗策略，以帮助预防牙龈假单胞菌相关疾病。

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.