Bacteriophage T4 Infection of Stationary Phase E. coli: Life after Log from a Phage Perspective.
Bacteriophage T4 Infection of Stationary Phase E. coli: Life after Log from a Phage Perspective.
复制标题
DOI：
10.3389/fmicb.2016.01391
复制
发表时间：
2016
影响因子：
5.2
通讯作者：
Kutter EM
中科院分区：
文献类型：
--
作者：
Bryan D;El-Shibiny A;Hobbs Z;Porter J;Kutter EM
事实上，所有噬菌体感染的研究都是在丰富的培养基中以指数方式生长的细菌。然而，在自然界中，细菌主要遇到非生长细胞。进入稳定期的细菌通常会激活经过充分研究的应激防御机制，从而彻底改变细胞，促进其长期存活。从生态学和治疗学的角度来看，了解这种情况下的噬菌体-宿主相互作用是非常重要的。在这里，我们表明噬菌体T4可以有效地结合，感染和杀死E。大肠杆菌在稳定期，无论是在存在和不存在的功能性稳定期西格玛因素，并探讨T4感染的稳定期细胞的反应，加入新鲜的营养素5或24小时后，感染。发现了一种意想不到的新反应模式。“休眠”模式是一种持续但可逆的休眠状态，其中感染的细胞产生至少一些噬菌体酶，但停止噬菌体发育，直到在产生噬菌体颗粒之前获得适当的营养物。我们的证据表明，在冬眠模式的块发生后，噬菌体发展的中间模式阶段;宿主DNA的分解和掺入的释放到噬菌体DNA的核苷酸表明，核苷酸合成复合物的酶，在中间模式的控制下，已制成和组装成一个功能状态。一旦获得新鲜的葡萄糖和氨基酸，标准的裂解感染过程迅速恢复，产生浓度高达1011个子代噬菌体（每个初始存在的细胞平均约40个噬菌体）。所有证据都与冬眠模式控制点位于中期模式和晚期模式T4基因表达之间一致。我们还观察到一种“清道夫”反应，即感染噬菌体利用仅有的几种营养物质在感染后2至5小时内产生少量子代。清道夫反应似乎能够产生不超过一个噬菌体的平均每个原始可用的细胞，很少，如果任何进一步的后代产生的细胞在这种模式下，即使新鲜的营养物质是可利用的。
Virtually all studies of phage infections investigate bacteria growing exponentially in rich media. In nature, however, phages largely encounter non-growing cells. Bacteria entering stationary phase often activate well-studied stress defense mechanisms that drastically alter the cell, facilitating its long-term survival. An understanding of phage-host interactions in such conditions is of major importance from both an ecological and therapeutic standpoint. Here, we show that bacteriophage T4 can efficiently bind to, infect and kill E. coli in stationary phase, both in the presence and absence of a functional stationary-phase sigma factor, and explore the response of T4-infected stationary phase cells to the addition of fresh nutrients 5 or 24 h after that infection. An unexpected new mode of response has been identified. “Hibernation” mode is a persistent but reversible dormant state in which the infected cells make at least some phage enzymes, but halt phage development until appropriate nutrients become available before producing phage particles. Our evidence indicates that the block in hibernation mode occurs after the middle-mode stage of phage development; host DNA breakdown and the incorporation of the released nucleotides into phage DNA indicate that the enzymes of the nucleotide synthesizing complex, under middle-mode control, have been made and assembled into a functional state. Once fresh glucose and amino acids become available, the standard lytic infection process rapidly resumes and concentrations of up to 1011 progeny phage (an average of about 40 phage per initially present cell) are produced. All evidence is consistent with the hibernation-mode control point lying between middle mode and late mode T4 gene expression. We have also observed a “scavenger” response, where the infecting phage takes advantage of whatever few nutrients are available to produce small quantities of progeny within 2 to 5 h after infection. The scavenger response seems able to produce no more than an average of one phage per originally available cell, and few if any further progeny are produced by cells in this mode even if fresh nutrients are made available later.