Prichard Amy, Sy Annika, Meyer Justin, Villa Elizabeth, Pogliano Joe
School of Biological Sciences, University of California San Diego, La Jolla, CA, 92093, USA.
Howard Hughes Medical Institute, University of California San Diego, La Jolla, CA, 92093, USA.
Sci Rep. 2025 Jan 11;15(1):1692. doi: 10.1038/s41598-024-64095-4.
As nucleus-forming phages become better characterized, understanding their unifying similarities and unique differences will help us understand how they occupy varied niches and infect diverse hosts. All identified nucleus-forming phages fall within the Chimalliviridae family and share a core genome of 68 unique genes including chimallin, the major nuclear shell protein. A well-studied but non-essential protein encoded by many nucleus-forming phages is PhuZ, a tubulin homolog which aids in capsid migration, nucleus rotation, and nucleus positioning. One clade that represents 24% of all currently known chimalliviruses lacks a PhuZ homolog. Here we show that Erwinia phage Asesino, one member of this PhuZ-less clade, shares a common overall replication mechanism with other characterized nucleus-forming phages despite lacking PhuZ. We show that Asesino replicates via a phage nucleus that encloses phage DNA and partitions proteins in the nuclear compartment and cytoplasm in a manner similar to previously characterized nucleus-forming phages. Consistent with a lack of PhuZ, however, we did not observe active positioning or rotation of the phage nucleus within infected cells. These data show that some nucleus-forming phages have evolved to replicate efficiently without PhuZ, providing an example of a unique variation in the nucleus-based replication pathway.
随着成核噬菌体的特征被更深入地了解,认识它们的统一相似性和独特差异将有助于我们理解它们如何占据不同的生态位并感染不同的宿主。所有已鉴定的成核噬菌体都属于Chimalliviridae科,共享一个由68个独特基因组成的核心基因组,其中包括主要核壳蛋白chimallin。许多成核噬菌体编码的一种经过充分研究但并非必需的蛋白质是PhuZ,它是一种微管蛋白同源物,有助于衣壳迁移、核旋转和核定位。在所有目前已知的chimalliviruses中,有一个分支占24%,缺乏PhuZ同源物。在这里,我们表明欧文氏菌噬菌体Asesino,这个无PhuZ分支的一个成员,尽管缺乏PhuZ,但与其他已表征的成核噬菌体具有共同的整体复制机制。我们表明,Asesino通过一个噬菌体核进行复制,该核将噬菌体DNA包裹起来,并以类似于先前表征的成核噬菌体的方式在核区室和细胞质中分配蛋白质。然而,与缺乏PhuZ一致,我们没有观察到感染细胞内噬菌体核的主动定位或旋转。这些数据表明,一些成核噬菌体已经进化到在没有PhuZ的情况下也能高效复制,这为基于核的复制途径中的一种独特变异提供了一个例子。