Pheromone‐mediated conjugative transfer of enterococcal plasmids can contribute to the dissemination of genes involved in antibiotic resistance, fitness, and virulence among co‐residents of mixed microbial communities. We have previously shown that intergeneric signaling by the Streptococcus gordonii strain Challis heptapeptide s.g.cAM373 (SVFILAA) induces an aggregation substance‐mediated mating response and facilitates plasmid transfer from Enterococcus faecalis cells carrying the pheromone‐responsive plasmid pAM373 to both pheromone‐producing and non‐pheromone‐producing oral streptococcal recipients. To further investigate the streptococcal pheromone‐like peptides, s.g.cAM373‐like sequences were identified in the signal sequences of streptococcal CamG lipoproteins and their abilities to induce a mating response in E. faecalis/pAM373 cells were examined. Synthetic heptamers with the consensus sequence (A/S)‐(I/V)‐F‐I‐L‐(A/V/T)‐(S/A) induced AS‐mediated clumping. The conserved pheromone ABC transporter encoded by S. gordonii genome loci SGO_RS02660 and SGO_RS02665 was identified and confirmed to be required for s.g.cAM373 activity. Functional assays of culture supernatants from representative oral and blood isolates of S. gordonii showed that in addition to strains encoding s.g.cAM373, strain SK120, encoding the newly identified pheromone s.g.cAM373‐V (SVFILVA), was able to induce enterococcal clumping, whereas strains SK6, SK8, SK9, and SK86 which encoded s.g.cAM373‐T (SVFILTA) did not elicit a detectable mating response. Absence of pheromone activity in supernatants of heterologous hosts encoding its CamG precursor suggested that s.g.cAM373‐T was not effectively processed and/or transported. Overall, these studies demonstrated the distribution of active pheromone peptides among strains of S. gordonii, and support a potential role for enterococcal–streptococcal communication in contributing to genetic plasticity in the oral metagenome.

中文翻译：

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信号链球菌肽，携带携带信息素反应性结合质粒pAM373的粪肠球菌。

信息素介导的肠球菌质粒的共轭转移可有助于在混合微生物群落的共居者中传播涉及抗生素抗性，适应性和毒力的基因。先前我们已经表明，戈登链球菌Challis七肽sgcAM373（SVFILAA）的属间信号传导诱导聚集物质介导的交配反应并促进粪肠球菌的质粒转移携带产生信息素和不产生信息素的口服链球菌受体的信息素应答质粒pAM373的细胞。为了进一步研究链球菌信息素样肽，在链球菌CamG脂蛋白的信号序列中鉴定出sgcAM373样序列，并检测了它们在粪肠球菌/ pAM373细胞中诱导交配反应的能力。具有共有序列（A / S）-（I / V）-F-I-L-（A / V / T）-（S / A）的合成七聚体诱导AS介导的团簇。鉴定由戈登氏链球菌基因组基因座SGO_RS02660和SGO_RS02665编码的保守信息素ABC转运蛋白，并确认其是sgcAM373活性所必需的。功能性测定从代表性的口腔和血液分离株的培养上清液戈登氏链球菌显示，除了编码sgcAM373的菌株外，编码新鉴定的信息素sgcAM373-V（SVFILVA）的菌株SK120还能够诱导肠球菌结块，而编码sgcAM373-T（ SVFILTA）没有引起可检测的交配反应。编码其CamG前体的异源宿主上清液中没有信息素活性，这表明sgcAM373-T没有得到有效的加工和/或运输。总的来说，这些研究表明戈尔氏链球菌菌株中活性信息素肽的分布，并支持肠球菌-链球菌交流在口腔基因组中遗传可塑性中的潜在作用。