Gene Expression and Regulation Section, Laboratory of Cell and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0830, USA.
Viruses. 2018 Jun 26;10(7):343. doi: 10.3390/v10070343.
The lytic bacteriophage T4 employs multiple phage-encoded early proteins to takeover the host. However, the functions of many of these proteins are not known. In this study, we have characterized the T4 early gene , located in a dispensable region of the T4 genome. We show that heterologous production of MotB is highly toxic to , resulting in cell death or growth arrest depending on the strain and that the presence of increases T4 burst size 2-fold. Previous work suggested that affects middle gene expression, but our transcriptome analyses of T4 vs. T4 wt infections reveal that only a few late genes are mildly impaired at 5 min post-infection, and expression of early and middle genes is unaffected. We find that MotB is a DNA-binding protein that binds both unmodified host and T4 modified [(glucosylated, hydroxymethylated-5 cytosine, (GHme-C)] DNA with no detectable sequence specificity. Interestingly, MotB copurifies with the host histone-like proteins, H-NS and StpA, either directly or through cobinding to DNA. We show that H-NS also binds modified T4 DNA and speculate that MotB may alter how H-NS interacts with T4 DNA, host DNA, or both, thereby improving the growth of the phage.
T4 噬菌体利用多种噬菌体编码的早期蛋白接管宿主。然而，这些蛋白的许多功能尚不清楚。在这项研究中，我们对 T4 早期基因进行了特征分析，该基因位于 T4 基因组的一个可分配区域。我们表明，异源生产 MotB 对毒性很高，导致细胞死亡或生长停滞，具体取决于菌株，并且的存在使 T4 爆发量增加了 2 倍。先前的工作表明 影响中期基因的表达，但我们对 T4 感染的转录组分析显示，只有少数晚期基因在感染后 5 分钟时受到轻微影响，早期和中期基因的表达不受影响。我们发现 MotB 是一种 DNA 结合蛋白，可与未修饰的宿主和 T4 修饰的 DNA（（葡萄糖基化、羟甲基化-5 胞嘧啶，(GHme-C））结合，没有可检测的序列特异性。有趣的是，MotB 与宿主组蛋白样蛋白 H-NS 和 StpA 直接或通过与 DNA 的共结合而共纯化。我们表明 H-NS 也与修饰的 T4 DNA 结合，并推测 MotB 可能改变 H-NS 与 T4 DNA、宿主 DNA 或两者的相互作用方式，从而提高噬菌体的生长。
