Ruby J D, Li H, Kuramitsu H, Norris S J, Goldstein S F, Buttle K F, Charon N W
Department of Microbiology and Immunology, Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown 26506-9177, USA.
J Bacteriol. 1997 Mar;179(5):1628-35. doi: 10.1128/jb.179.5.1628-1635.1997.
Treponema denticola is an anaerobic, motile, oral spirochete associated with periodontal disease. We found that the periplasmic flagella (PFs), which are located between the outer membrane sheath and cell cylinder, influence its morphology in a unique manner. In addition, the protein composition of the PFs was found to be quite complex and similar to those of other spirochetes. Dark-field microscopy revealed that most wild-type cells had an irregular twisted morphology, with both planar and helical regions, and a minority of cells had a regular right-handed helical shape. High-voltage electron microscopy indicated that the PFs, especially in those regions of the cell which were planar, wrapped around the cell body axis in a right-handed sense. In those regions of the cell which were helical or irregular, the PFs tended to lie along the cell axis. The PFs caused the cell to form the irregular shape, as two nonmotile, PF-deficient mutants (JR1 and HL51) were no longer irregular but were right-handed helices. JR1 was isolated as a spontaneously occurring nonmotile mutant, and HL51 was isolated as a site-directed mutant in the flagellar hook gene flgE. Consistent with these results is the finding that wild-type cells with their outer membrane sheath removed were also right-handed helices similar in shape to JR1 and HL51. Purified PFs were analyzed by two-dimensional gel electrophoresis, and several protein species were identified. Western blot analysis using antisera to Treponema pallidum PF proteins along with N-terminal amino acid sequence analysis indicated T. denticola PFs are composed of one class A sheath protein of 38 kDa (FlaA) and three class B proteins of 35 kDa (FlaB1 and FlaB2) and one of 34 kDa (FlaB3). The N-terminal amino acid sequences of the FlaA and FlaB proteins of T. denticola were most similar to those of T. pallidum and Treponema phagedenis. Because these proteins were present in markedly reduced amounts or were absent in HL51, PF synthesis is likely to be regulated in a hierarchy similar to that found for flagellar. synthesis in other bacteria.
齿垢密螺旋体是一种与牙周病相关的厌氧、具运动性的口腔螺旋体。我们发现，位于外膜鞘和细胞圆柱体之间的周质鞭毛（PFs）以独特的方式影响其形态。此外，还发现PFs的蛋白质组成相当复杂，与其他螺旋体的蛋白质组成相似。暗视野显微镜显示，大多数野生型细胞具有不规则的扭曲形态，有平面区域和螺旋区域，少数细胞具有规则的右旋螺旋形状。高压电子显微镜表明，PFs，特别是在细胞的平面区域，以右旋方向围绕细胞体轴缠绕。在细胞的螺旋或不规则区域，PFs倾向于沿细胞轴排列。PFs使细胞形成不规则形状，因为两个无运动能力的、缺乏PFs的突变体（JR1和HL51）不再是不规则的，而是右旋螺旋体。JR1是作为自发出现的无运动能力突变体分离出来的，HL51是作为鞭毛钩基因flgE中的定点突变体分离出来的。与这些结果一致的是，去除外膜鞘的野生型细胞也是形状与JR1和HL51相似的右旋螺旋体。通过二维凝胶电泳分析纯化的PFs，并鉴定了几种蛋白质种类。使用针对梅毒螺旋体PF蛋白的抗血清进行的蛋白质印迹分析以及N端氨基酸序列分析表明，齿垢密螺旋体PFs由一种38 kDa的A类鞘蛋白（FlaA）和三种35 kDa的B类蛋白（FlaB1和FlaB2）以及一种34 kDa的蛋白（FlaB3）组成。齿垢密螺旋体FlaA和FlaB蛋白的N端氨基酸序列与梅毒螺旋体和噬齿密螺旋体的最为相似。因为这些蛋白质在HL51中的含量明显减少或不存在，PF的合成可能以与其他细菌中鞭毛合成相似的层次进行调控。
