Study on the Iron-Acquisition Mechanism of Periodontal Bacteria

铁是一种必需的细菌营养素，在体内不能自由地被细菌利用，因为铁与宿主铁结合蛋白如转铁蛋白、乳铁蛋白和血红蛋白复合。然而，致病菌发展特定的铁摄取系统，包括产生特定的细胞铁结合蛋白以在体内获得铁。对于牙周细菌，人们对其铁吸收系统知之甚少。在这项研究中，我们确定了牙周细菌，放线杆菌放线菌伴和牙龈卟啉单胞菌的铁吸收基因。结果表明：1）伴放线放线杆菌：这两个铁蛋白基因位于伴放线杆菌Y 4的一个调控基因actX的上游。铁蛋白是一种细菌铁结合蛋白，在细菌细胞中起着铁的获取和储存的作用。对伴放线菌Y 4的铁蛋白基因进行了克隆和序列分析。它们由486 bp（161个氨基酸）组成， 关于我们 ids）和498 bp（165个氨基酸）的开放阅读框。它们与流感嗜血杆菌铁蛋白基因的同源性分别为80%和85%。Western blotting分析表明，与抗大肠杆菌铁蛋白兔血清反应的两种细胞蛋白（约20 kDa）在伴放线放线菌Y 4细胞中得到表达。2）牙龈卟啉单胞菌：牙龈卟啉单胞菌生长需要氯化血红素。采用聚合酶链反应（PCR）方法对生姜拟杆菌的氯化血红素结合蛋白基因进行了克隆。从脆弱拟杆菌血红素摄取蛋白基因（hupA）设计用于PCR的寡核苷酸引物。从牙龈卟啉单胞菌FDC 381基因组DNA中扩增出约1.3-kb的DNA片段，并分析DNA序列。扩增片段的部分DNA序列与姜疫霉的血凝素基因和蛋白酶基因有较高的同源性。这些结果表明牙龈卟啉单胞菌可能通过这些基因产物捕获红细胞并分解红细胞以获得氯化血红素。少

Iron, an essential bacterial nutrient, is not freely available for bacteria in vivo because iron is complexed with host iron-binding proteins such as transferrin, lactoferrin and hemoglobin. However, pathogenic bacteria develop specific iron-uptake systems including the production of specific cellular iron binding proteins to acquire iron in vivo. For periodontal bacteria, little is known about their iron-uptake system. In this study, we determined the genes for iron uptake in periodontal bacteria, Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis. The following results were obtained.1) A.actinomycetemcomitans :The two ferritin genes were found in the upstream of a regulatory gene, actX of A.actinomycetemcomitans Y4. Ferritin is a bacterial iron binding protein, which acts iron acquisition and storage in bacterial cells. The ferritin genes in A.actinomycetemcomitans Y4 were cloned and their DNA sequence analyses were performed. They are consisted of 486 bp (161 amino ac … More ids) and 498 bp(165amino acids) open reading frames. They exhibited 80 % and 85 % homology with Haemophilus influenzae ferritin genes. The Western blotting analysis showed the two cellular proteins(approximately 20kDa), reacted with anti-Escherichia coli ferritin rabbit serum were expressed in A.actinomycetemcomitans Y4 cells.2) P.gingivalis :P.gingivalis requires hemin for its growth. The putative hemin biding protein genes were determined for P.gingi va/is by polymerase chain reaction method. The oligonucleotide primers for the PCR were designed from the Bacteroides fragilis hemin-uptake protein gene(hupA). Approximate 1.3-kb DNA fragments were amplified from P.gingivahs FDC 381 genomic DNA and the DNA sequences were analyzed. The partial DNA sequences of the amplified DNA fragments showed high homologies with the P.gingi valis hemagglutinin gene and protease genes. These results indicate that P.gingivalis might capture to erythrocytes and decompose them to acquire hemin by these gene products. Less