A study Of ora| streptococcal histone-like protein and virulence mechanism

中间链球菌与内源性感染有关，导致口腔和深部部位（如脑和肝脏）脓肿。组蛋白样蛋白（HLP）结合DNA和RNA分子、脂壁酸和上皮细胞，在细菌物种中具有良好的保守性，并诱导巨噬细胞产生白细胞介素(IL)-1和肿瘤坏死因子(TNF)-α。本研究采用聚合酶链式反应（PCR）技术，以化脓性葡萄球菌hip基因为引物，从染色体DNA中克隆出中间葡萄球菌HLP （HLPSi）编码基因，并与谷胱甘肽s -转移酶（GST）融合载体连接。编码的HLPSi有91个氨基酸；其分子量为9603，等电点为10.21。该序列与化脓性葡萄球菌A374和金黄色葡萄球菌Mu50的HLP序列具有高度的同源性，在氨基酸水平上与麻风分枝杆菌（ML-LBP21）的一个21 -kDa分子具有高度的同源性。利用抗HLPSi抗体和酶联免疫吸附法对中间葡萄球菌进行免疫电镜观察，发现部分HLPSi位于细胞表面，重组HLPSi与肝素结合。我们的研究结果表明，细菌细胞产生的HLP可能在发病机制中发挥多种作用，帮助细菌与感染宿主内的靶组织结合，并可能导致感染部位的组织损伤。

Streptococcus intermedius is associated with endogenous infections leading to abscesses in the oral cavity and deep-seated sites, such as the brain and liver. Histone-like protein (HLP), which binds to DNA and RNA molecules and to lipoteichoic acid and epithelial cells, is well conserved among bacterial species and induces macrophages to produce interleukin (IL)-1 and tumor necrosis factor (TNF)-α. In this study, we cloned the gene encoding S. intermedius HLP (HLPSi) from chromosomal DNA by use of the polymerase chain reaction (PCR) using the primers based on S. pyogenes hip gene and ligated to the glutathione S-transferase (GST) fusion vector. The encoded HLPSi had 91 amino acids; and its molecular weight and isoelectric point calculated from the sequence were 9,603 and 10.21 , respectively. The sequence of HLPSi had a high identity with those sequences of the HLP of S. pyogenes A374 and Staphylococcus aureus Mu50 and showed high homology with a 21 -kDa molecule of Mycobavterium leprae (ML-LBP21) at the amino acid level. The immunoelectron micrograph of S. intermedius by anti-HLPSi antibody and ELISA demonstrated that a part of HLPSi was localized on the cell surface and that recombinant HLPSi (rHLPSi) bound to heparin. Our results suggest that HLP produced from bacterial cells may play various roles in pathogenesis by helping the bacteria to bind to their target tissue within the infected host and may contribute to tissue injury at the infection site.