The Porphyromonas gingivalis Mfa1 fimbria is composed of the Mfa1 to Mfa5 proteins, encoded by the mfa1 to mfa5 genes, respectively, which are tandemly arranged on chromosomes. A recent study discovered that many P. gingivalis strains possess two mfa5 genes (called herein mfa5-1 and mfa5-2), which are also in tandem. This study examined the transcriptional unit and activity of mfa-cluster genes in strains with one (the ATCC 33277 and TDC60 strains) and two (the HG66 and A7436 strains) mfa5 genes. Complementary DNA was prepared from the total RNA extracted from the bacterial cells in the logarithmic growth phase using a random primer. PCR analysis for the intergenic regions from mfa1 to mfa5 or mfa5-2 showed that mfa1 to mfa5 or mfa5-2 formed a polycistronic gene cluster. Quantitative real-time PCR showed that the mfa1 transcription was 5–10 times higher than that of mfa2 in all the strains. However, mfa2 to mfa5 mostly showed a comparable expression. Both mfa5 genes were comparably transcribed in HG66 and A7436 strains. The transcriptional levels were almost consistent with the respective protein expression levels. In silico analysis identified a transcriptional terminator structure in the intergenic region between mfa1 and mfa2 that was probably responsible for the decreased transcription rate of mfa2 and the downstream genes.

中文翻译：

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具有一个和两个 mfa5 基因的牙龈卟啉单胞菌菌株中 mfa 簇基因的转录分析

牙龈卟啉单胞菌 Mfa1 菌毛由 Mfa1 至 Mfa5 蛋白组成，分别由mfa1至mfa5基因编码，串联排列在染色体上。最近的一项研究发现，许多P. gingivalis菌株拥有两个mfa5基因（本文称为mfa5-1和mfa5-2），它们也是串联的。本研究检测了一种（ATCC 33277 和 TDC60 菌株）和两种（HG66 和 A7436 菌株）mfa5菌株中mfa-簇基因的转录单位和活性基因。使用随机引物从处于对数生长期的细菌细胞中提取的总RNA制备互补DNA。mfa1到mfa5或mfa5-2 的基因间区域的PCR 分析表明mfa1到mfa5或mfa5-2形成了一个多顺反子基因簇。定量实时 PCR 表明，在所有菌株中，mfa1转录比mfa2转录高 5-10 倍。然而，mfa2到mfa5大多表现出相当的表达。两个mfa5基因在 HG66 和 A7436 菌株中的转录水平相当。转录水平几乎与各自的蛋白质表达水平一致。计算机分析确定了mfa1和mfa2之间基因间区域的转录终止子结构，这可能是mfa2和下游基因转录率降低的原因。