Integrated Research on pathogenic factors of periodontal pathogens

伴放线放线杆菌细胞毒性膨胀毒素(CDT)的研究：CDT是一种由三个亚基组成的蛋白质毒素，即CDtA、CDtB和CDtC。放线菌伴生菌CDtA在其C端含有脂盒结构域，是脂类修饰的共有结构域。我们证明了在大肠杆菌中表达的放线菌伴生菌CDtA中的16个半胱氨酸被氚酸棕榈酸酯或甘油修饰。CDtA的转录后合成被球霉素抑制，球霉素是一种信号肽II的特异性抑制剂，是脂蛋白的信号肽酶。我们还证明了在大肠杆菌中表达的CDtA在其周质空间的N端被进一步加工并转化为CDtA‘。此外，我们还证明了CDTA的脂质修饰对于CDT复合体(全毒素)分泌到培养基中是重要的。我们还证明了在CdtB编码序列中存在SNP。因此，来自临床分离的放线菌伴生菌的cdtB的第281个氨基酸是H或R。用…进行生物测定。通过定点突变获得更多的TH突变的CDtB，表明281位的正电荷氨基酸是CDT活性的关键。放线菌伴生菌外膜蛋白的研究：我们先前已经证明放线菌伴生菌具有多种外膜蛋白(OMP)和Omp100具有多效性的生物学活性。我们发现Omp100是一种主要的细菌成分，可以诱导人牙龈上皮细胞产生抗菌肽。抑制物分析表明，hBD2产生的信号途径不是通过核因子-kB途径，而是MAP-激酶途径。Omp100通过与纤维连接蛋白结合，通过整合素α-β途径诱导hBD2的产生。细菌附着于表皮细胞诱导的细胞因子也可诱导hBD2的表达。牙周病原菌诱导抗菌肽的研究。通过使用合成肽，我们评估了牙周病原菌对抗菌肽的敏感性。我们的数据表明，LL37和β-防御素对牙周病致病菌具有很强的抗菌活性。较少

Study on A. actinomycetemcomitans Cytolethal Distending Toxin (CDT) : CDT is a protein toxin composed of three subunit, CdtA, CdtB and CdtC. A. actinommycetemcomitans CdtA posseses lipobox, consensus domain for lipid modification in its C-terminal. We demonstrated that 16^<th> cys in A. actinommycetemcomitans CdtA expressed in E. coli was modified with tritiated palmitate or glycerol. Posttranscriptional prosesing of the CdtA is inhibited by globomycin, a specific inhibitor for signal peptidase II, signal peptidase for lipoprotein. We also demonstrated that the CdtA expressed in E. coli is further processed at its N-terminal in periplasmic space and is converted to CdtA'. Furthermore, we showed that lipid-modification of CdtA is important for the secretion of Cdt complex (holotoxin) into culture media. We also demonstrated that there is a SNP in cdtB coding sequences. Hence, 281th amino acid of CdtB derived from clinically isolated A. actinomycetemcomitans is either H or R. Bioassay wi … More th mutated CdtB by site-directed mutagenesis indicated that positively charged amino acid at 281 is critical for Cdt activity.Study on A. actinomycetemcomitans outer membrane protein: We have previously demonstrated that A. actinomycetemcomitans posseses several outer membrane proteins (Omp) and Omp100 has pleiotropic biological activities. We identified Omp100 as a major bacterial component inducing production of antimicrobial peptides from human gingival epidermal cells. Inhibitor assay strongy suggested that signaling pathway for hBD2 production is not by NF-kB pathway but by MAP-kinase pathway. Omp100 induces hBD2 production through associating with fibronectin and by way of integrin alpha5betal pathway. Cytokine induced by attachment of bacteria to epidermal cells also induces hBD2 expression.Study on inducibility of antimicrobial peptides by periodontopathogenic bacteria. By using synthtic peptides, we evaluated susceptibility of periodontopathogenic bacteria to antimicrobial peptides. Our data indicated that LL37 and beta-defensin showed potent antimicrobial activity against periodontapathogenic bacteria. Less