Role of ECF sigma factors of Porphyromonas gingivalis on biofilm formation or virulence

细胞质外功能(ECF)sigma因子是已知的将环境信号的变化传递给基因表达的特定反应的因子。在牙周病原体牙龈卟啉单胞菌的基因组中，鉴定出6种ECF sigma因子。为了阐明ECF西格玛因子在该细菌中的作用，构建了携带ECF西格玛因子编码基因的染色体突变株。结果表明，突变株PG0162(PGN_0274)表现出较低的牙龈蛋白酶活性，且与野生型菌株相比，突变株PGN_1740对过氧化氢敏感。此外，与野生型相比，pGN_0274和pGN_1740缺陷突变体增加了生物膜的形成。总而言之，我们的研究表明，每个ECF西格玛因子都协同参与了牙龈假单胞菌的毒力。

Extracytoplasmic function (ECF) sigma factors are known to transmit changes in environmental signals to specific responses in gene expression.In the genome of periodontal pathogen Porphyromonas gingivalis, six ECF sigma factors were identified. To elucidate the role of ECF sigma factors in this bacterium, chromosomal mutants carrying a disruption in each ECF sigma factor-encoding gene were constructed. Our results indicate that PG0162 (PGN_0274) mutant showed decreased gingipain protease activity.Furthermore, the mutant defective in PG1827 (PGN_1740) was sensitive to hydrogen peroxide compared with the wild-type strain. In addition, the PGN_0274 and PGN_1740-defective mutants had increased biofilm formation compared with the wild type. Collectively, our studies demonstrate that each ECF sigma factor is cooperatively involved in P. gingivalis virulence.