Control of the transcription of a short gene encoding a cyclic peptide in Streptococcus thermophilus:: a new quorum-sensing system?
Control of the transcription of a short gene encoding a cyclic peptide in Streptococcus thermophilus:: a new quorum-sensing system?
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DOI：
10.1128/jb.01057-07
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发表时间：
2007-12-01
影响因子：
3.2
通讯作者：
Monnet, Veronique
中科院分区：
文献类型：
--
作者：
Ibrahim, Mariam;Guillot, Alain;Monnet, Veronique
革兰氏阳性细菌分泌多种肽，这些肽经常进行翻译后修饰，并且是参与细菌通讯的抗菌剂或信息素。我们的目标是鉴定嗜热链球菌（一种广泛用于乳制品技术中与其他细菌相关的非致病性细菌）分泌的肽，并了解它们在细胞间通讯中的潜在作用。使用反相液相色谱、质谱和 Edman 测序，我们分析了在不含肽的培养基中生长的三种嗜热链球菌菌株（CNRZ1066、LMG18311 和 LMD-9）的培养物上清液。我们在培养物上清液中鉴定出多种肽，其中一些肽在三种菌株中发现，而另一些则是 LMD-9 菌株特有的。我们的研究重点是嗜热链球菌 LMD-9 分泌的一种新的修饰肽，命名为 Pep1357C。该肽包含 9 个氨基酸，并在翻译后修饰（很可能是脱氢）中丢失了 2 Da，导致 Lys2 和 Trp6 残基之间形成连接。 Pep1357C 的产生及其编码基因的转录取决于培养基成分和生长阶段。此外，我们证明，在短疏水肽、转录调节剂或寡肽转运系统的合成失活的突变体中，编码 Pep1357C 的基因的转录急剧减少。综上所述，我们的结果使我们推断 Pep1357C 编码基因的转录是由新的群体感应系统控制的。
Gram-positive bacteria secrete a variety of peptides that are often subjected to posttranslational modifications and that are either antimicrobials or pheromones involved in bacterial communication. Our objective was to identify peptides secreted by Streptococcus thermophilus, a nonpathogenic bacterium widely used in dairy technology in association with other bacteria, and to understand their potential roles in cell-cell communication. Using reverse-phase liquid chromatography, mass spectrometry, and Edman sequencing, we analyzed the culture supernatants of three S. thermophilus strains (CNRZ1066, LMG18311, and LMD-9) grown in a medium containing no peptides. We identified several peptides in the culture supernatants, some of them found with the three strains while others were specific to the LMD-9 strain. We focused our study on a new modified peptide secreted by S. thermophilus LMD-9 and designated Pep1357C. This peptide contains 9 amino acids and lost 2 Da in a posttranslational modification, most probably a dehydrogenation, leading to a linkage between the Lys2 and Trp6 residues. Production of Pep1357C and transcription of its encoding gene depend on both the medium composition and the growth phase. Furthermore, we demonstrated that transcription of the gene coding for Pep1357C is drastically decreased in mutants inactivated for the synthesis of a short hydrophobic peptide, a transcriptional regulator, or the oligopeptide transport system. Taken together, our results led us to deduce that the transcription of the Pep1357C-encoding gene is controlled by a new quorum-sensing system.