Lethal protein produced in response to competition between sibling bacterial colonies
Lethal protein produced in response to competition between sibling bacterial colonies
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DOI：
10.1073/pnas.1001062107
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发表时间：
2010-04-06
影响因子：
11.1
通讯作者：
Swinney, Harry L.
中科院分区：
文献类型：
--
作者：
Be'er, Avraham;Ariel, Gil;Swinney, Harry L.
在低营养琼脂培养基上生长的姐妹类芽孢杆菌（Paenibacillus dendritiformis）细菌菌落通过分泌致死因子而相互抑制生长。分泌物的分析揭示了枯草杆菌蛋白酶（蛋白酶）和12 kDa的蛋白质，称为同胞致死因子（SLF）的存在。纯化的枯草杆菌蛋白酶促进树状毕赤酵母菌落的生长和扩增，而Slf是致死的并且裂解培养物中的树状毕赤酵母细胞。S1f由属于功能未知的细菌基因大家族的基因编码，并且该基因被预测编码约20kDa的蛋白质，称为树状姊妹细菌素。产生了20 kDa的重组蛋白，发现其无活性，但暴露于枯草杆菌蛋白酶导致裂解为活性的12 kDa形式。实验结果结合数学模型表明，枯草杆菌蛋白酶对殖民地的生长有调节作用。低于阈值浓度，枯草杆菌蛋白酶促进菌落生长和扩增。然而，一旦它超过阈值，如在竞争菌落之间的界面处发生的，则Slf被分泌到培养基中以通过细菌细胞的裂解快速降低细胞密度。在其他细菌物种中存在编码树状细菌素同源物的基因，表明这种自我调节菌落生长的机制可能不仅限于树状假单胞菌。
Sibling Paenibacillus dendritiformis bacterial colonies grown on low-nutrient agar medium mutually inhibit growth through secretion of a lethal factor. Analysis of secretions reveals the presence of subtilisin (a protease) and a 12 kDa protein, termed sibling lethal factor (Slf). Purified subtilisin promotes the growth and expansion of P. dendritiformis colonies, whereas Slf is lethal and lyses P. dendritiformis cells in culture. Slf is encoded by a gene belonging to a large family of bacterial genes of unknown function, and the gene is predicted to encode a protein of approximately 20 kDa, termed dendritiformis sibling bacteriocin. The 20 kDa recombinant protein was produced and found to be inactive, but exposure to subtilisin resulted in cleavage to the active, 12 kDa form. The experimental results, combined with mathematical modeling, show that subtilisin serves to regulate growth of the colony. Below a threshold concentration, subtilisin promotes colony growth and expansion. However, once it exceeds a threshold, as occurs at the interface between competing colonies, Slf is then secreted into the medium to rapidly reduce cell density by lysis of the bacterial cells. The presence of genes encoding homologs of dendritiformis sibling bacteriocin in other bacterial species suggests that this mechanism for self-regulation of colony growth might not be limited to P. dendritiformis.