Instituto de Biología Molecular Eladio Viñuela (Consejo Superior de Investigaciones Científicas), Centro de Biología Molecular Severo Ochoa (Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid), Universidad Autónoma, Canto Blanco, 28049 Madrid, Spain.
Proc Natl Acad Sci U S A. 2012 Apr 10;109(15):5723-8. doi: 10.1073/pnas.1203824109. Epub 2012 Mar 26.
Organization of replicating prokaryotic genomes requires architectural elements that, similarly to eukaryotic systems, induce topological changes such as DNA supercoiling. Bacteriophage 29 protein p6 has been described as a histone-like protein that compacts the viral genome by forming a nucleoprotein complex and plays a key role in the initiation of protein-primed DNA replication. In this work, we analyze the subcellular localization of protein p6 by immunofluorescence microscopy and show that, at early infection stages, it localizes in a peripheral helix-like configuration. Later, at middle infection stages, protein p6 is recruited to the bacterial nucleoid. This migrating process is shown to depend on the synthesis of components of the 29 DNA replication machinery (i.e., terminal protein and DNA polymerase) needed for the replication of viral DNA, which is required to recruit the bulk of protein p6. Importantly, the double-stranded DNA-binding capacity of protein p6 is essential for its relocalization at the nucleoid. Altogether, the results disclose the in vivo organization of a viral histone-like protein in bacteria.
原核生物基因组的复制组织需要类似于真核系统的结构元件，这些元件能够诱导拓扑结构的变化，如 DNA 超螺旋化。噬菌体 29 蛋白 p6 被描述为一种组蛋白样蛋白，它通过形成核蛋白复合物来压缩病毒基因组，并在蛋白质起始的 DNA 复制中发挥关键作用。在这项工作中，我们通过免疫荧光显微镜分析了蛋白 p6 的亚细胞定位，并表明在早期感染阶段，它定位于外周螺旋状结构中。后来，在中期感染阶段，蛋白 p6 被招募到细菌核区。迁移过程依赖于 29 型 DNA 复制机制的合成（即末端蛋白和 DNA 聚合酶），这些蛋白是复制病毒 DNA 所必需的，病毒 DNA 的复制是招募大量蛋白 p6 的必要条件。重要的是，蛋白 p6 的双链 DNA 结合能力对于其在核区的重新定位是必不可少的。总之，这些结果揭示了一种病毒组蛋白样蛋白在细菌中的体内组织。
