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首页> 外文期刊>Infection and immunity >Expression of the tpr Protease Gene ofPorphyromonas gingivalis Is Regulated by Peptide Nutrients
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Expression of the tpr Protease Gene ofPorphyromonas gingivalis Is Regulated by Peptide Nutrients

机译：肽营养素调节牙龈卟啉单胞菌tpr蛋白酶基因的表达

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The Tpr protease of Porphyromonas gingivalis W83 is a membrane-associated enzyme capable of hydrolyzing chromogenic substrates for trypsin and bacterial collagenases. A previous study by us indicated that Tpr expression was increased under conditions of nutrient limitation. In the present study, we further characterized expression of the tpr gene using atpr::lacZ reporter gene construct under a range of nutrient conditions. In P. gingivalis, transcription of tpr was initiated 215 bp upstream of the coding region and regulation of tpr expression was at the level of transcription. Deletion mutations in the tprupstream region identified the promoter region immediately upstream of the transcription start site, determined by primer extension analysis. Three identical 17-bp direct repeats identified within the 5′ end oftpr mRNA were involved in tpr regulation. In anEscherichia coli background, tpr transcription was initiated after an AT-rich region upstream of tpr but not at the P. gingivalis start site. Tpr expression inP. gingivalis was suppressed by the addition of peptide and protein nutrients to a peptide-limited growth medium but was only slightly affected by addition of free amino acids. Low-molecular-weight fractions of brain heart infusion rich in phenylalanine, proline, and alanine had the greatest inhibitory effects on expression of thetpr::lacZ construct. Addition of the dipeptide phenylalanyl-phenylalanine to the growth medium resulted in a 10-fold decrease in tpr expression. This suggests that specific phenylalanine-containing peptides are a major factor controlling Tpr expression. Neither hemin starvation, heat shock, nor pH change had significant effects on Tpr expression.
机译：牙龈卟啉单胞菌W83的Tpr蛋白酶是一种膜相关酶，能够水解胰蛋白酶和细菌胶原酶的生色底物。我们先前的研究表明，在营养限制条件下Tpr表达增加。在本研究中，我们进一步使用 tpr :: lacZ 报告基因构建体在一系列营养条件下表征了 tpr 基因的表达。在 P中。牙龈炎时， tpr 的转录在编码区上游215 bp处开始，而 tpr 表达的调节处于转录水平。通过引物延伸分析确定 tpr 上游区域中的缺失突变，鉴定出转录起始位点紧邻上游的启动子区域。在 tpr 调控中涉及到在 tpr mRNA 5'末端鉴定出的三个相同的17 bp直接重复序列。在大肠杆菌背景中， tpr 转录是在 tpr 上游的富AT区域之后而不是在 P处开始的。 gingivalis 起始站点。 Tem表达在 P中。肽限制生长培养基中添加肽和蛋白质营养物质可抑制牙龈炎，但游离氨基酸的添加只会轻微影响牙龈。富含苯丙氨酸，脯氨酸和丙氨酸的低分子脑心输液对 tpr :: lacZ 构建体的表达具有最大的抑制作用。向生长培养基中添加二肽苯丙氨酰-苯丙氨酸会导致 tpr 表达降低10倍。这表明特定的含苯丙氨酸的肽是控制Tpr表达的主要因素。血红素饥饿，热休克或pH变化均未对Tpr表达产生显着影响。

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