An essential and highly selective protein import pathway encoded by nucleus- forming phage

• 成果类型: Article
• 署名作者: Morgan, Chase J.; Enustun, Eray; Armbruster, Emily G.; Birkholz, Erica A.; Prichard, Amy; Forman, Taylor; Aindow, Ann; Wannasrichan, Wichanan; Peters, Sela; Inlow, Koe; Shepherd, Isabelle L.; Razavilar, Alma; Chaikeeratisak, Vorrapon; Adler, Benjamin A.; Cress, Brady F.; Doudna, Jennifer A.; Pogliano, Kit; Villa, Elizabeth; Corbett, Kevin D.; Pogliano, Joe
• 署名单位: University of California System; University of California San Diego; Chulalongkorn University; University of California System; University of California Berkeley; University of California System; University of California Berkeley; University of California System; University of California Berkeley; University of California System; University of California Berkeley; University of California System; University of California Berkeley; Howard Hughes Medical Institute; United States Department of Energy (DOE); Lawrence Berkeley National Laboratory; United States Department of Energy (DOE); Lawrence Berkeley National Laboratory; University of California System; University of California San Diego; Howard Hughes Medical Institute; University of California System; University of California San Diego
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-14920
• DOI: 10.1073/pnas.2321190121
• 发表日期: 2024-05-07
• 关键词: dna; translocases; replication; transport; viruses

摘要

Targeting proteins to specific subcellular destinations is essential in prokaryotes, eukaryotes, and the viruses that infect them. Chimalliviridae phages encapsulate their genomes in a nucleus - like replication compartment composed of the protein chimallin (ChmA) that excludes ribosomes and decouples transcription from translation. These phages selectively partition proteins between the phage nucleus and the bacterial cytoplasm. Currently, the genes and signals that govern selective protein import into the phage nucleus are unknown. Here, we identify two components of this protein import pathway: a species - specific surface - exposed region of a phage intranuclear protein required for nuclear entry and a conserved protein, PicA (Protein importer of chimalliviruses A), that facilitates cargo protein trafficking across the phage nuclear shell. We also identify a defective cargo protein that is targeted to PicA on the nuclear periphery but fails to enter the nucleus, providing insight into the mechanism of nuclear protein trafficking. Using CRISPRi - ART protein expression knockdown of PicA, we show that PicA is essential early in the chimallivirus replication cycle. Together, our results allow us to propose a multistep model for the Protein Import Chimallivirus pathway, where proteins are targeted to PicA by amino acids on their surface and then licensed by PicA for nuclear entry. The divergence in the selectivity of this pathway between closely related chimalliviruses implicates its role as a key player in the evolutionary arms race between competing phages and their hosts.