Li H, Arakawa S, Deng Q D, Kuramitsu H
Department of Oral Biology, State University of New York, Buffalo, New York 14214, USA.
Infect Immun. 1999 Feb;67(2):694-9. doi: 10.1128/IAI.67.2.694-699.1999.
Immediately downstream from the previously isolated Treponema denticola ATCC 35405 prtB gene coding for a chymotrypsinlike protease activity, an open reading frame, ORF3, was identified which shared significant homology with the highly conserved domains (HCDs) of bacterial methyl-accepting chemotaxis proteins (MCPs). Nucleotide sequencing of this ORF revealed that the gene would code for a protein with a size of approximately 41 kDa. In addition, this sequence contained a domain which was virtually identical to the HCD of a recently characterized MCP, DmcA, of strain 35405. Therefore, this ORF was named dmcB. Northern blot analysis suggested that dmcB was part of an operon structure containing prtB. Insertional inactivation of dmcB utilizing an ermF-ermAM cassette resulted in a mutant with decreased chemoattraction toward nutrient supplements. In addition, the mutant displayed an altered pattern of methylated proteins under conditions of chemotaxis. Inactivation of the dmcB gene also attenuated the methylation of the DmcA protein. These results suggest that the dmcB gene codes for an MCP in T. denticola which may interact with other MCPs in these organisms.
在先前分离出的编码类胰凝乳蛋白酶活性的齿垢密螺旋体ATCC 35405 prtB基因的紧下游，鉴定出一个开放阅读框ORF3，它与细菌甲基接受趋化蛋白（MCP）的高度保守结构域（HCD）具有显著同源性。对该ORF进行核苷酸测序表明，该基因编码的蛋白质大小约为41 kDa。此外，该序列包含一个结构域，与最近鉴定的35405菌株的MCP DmcA的HCD几乎相同。因此，该ORF被命名为dmcB。Northern印迹分析表明，dmcB是包含prtB的操纵子结构的一部分。利用ermF-ermAM盒对dmcB进行插入失活，产生了一个对营养补充剂趋化性降低的突变体。此外，该突变体在趋化条件下显示出甲基化蛋白质的模式改变。dmcB基因的失活也减弱了DmcA蛋白的甲基化。这些结果表明，dmcB基因在齿垢密螺旋体中编码一种MCP，它可能与这些生物体中的其他MCP相互作用。
