8fne | pdb_00008fne
phiPA3 PhuN Tetramer, p2
Structural highlights
FunctionMALE_ECOLI Involved in the high-affinity maltose membrane transport system MalEFGK. Initial receptor for the active transport of and chemotaxis toward maltooligosaccharides.CHMA_BPPA3 Self-assembles to forms a proteinaceous shell that encloses the viral DNA and compartmentalizes proteins and DNA during viral infection (PubMed:28813669). This micrometer-scale compartment contains narrow pores and is the site of viral replication, with the proteins involved in DNA replication localized inside (By similarity). Provides a surface for docking of capsids during packaging (PubMed:28813669). Probably protects the viral genome against host defenses (By similarity).[UniProtKB:B3FIW8][1] Publication Abstract from PubMedTo protect themselves from host attack, numerous jumbo bacteriophages establish a phage nucleus-a micron-scale, proteinaceous structure encompassing the replicating phage DNA. Bacteriophage and host proteins associated with replication and transcription are concentrated inside the phage nucleus while other phage and host proteins are excluded, including CRISPR-Cas and restriction endonuclease host defense systems. Here, we show that nucleus fragments isolated from varphiPA3 infected Pseudomonas aeruginosa form a 2-dimensional lattice, having p2 or p4 symmetry. We further demonstrate that recombinantly purified primary Phage Nuclear Enclosure (PhuN) protein spontaneously assembles into similar 2D sheets with p2 and p4 symmetry. We resolve the dominant p2 symmetric state to 3.9 A by cryo-EM. Our structure reveals a two-domain core, organized into quasi-symmetric tetramers. Flexible loops and termini mediate adaptable inter-tetramer contacts that drive subunit assembly into a lattice and enable the adoption of different symmetric states. While the interfaces between subunits are mostly well packed, two are open, forming channels that likely have functional implications for the transport of proteins, mRNA, and small molecules. The varphiPA3 phage nucleus is enclosed by a self-assembling 2D crystalline lattice.,Nieweglowska ES, Brilot AF, Mendez-Moran M, Kokontis C, Baek M, Li J, Cheng Y, Baker D, Bondy-Denomy J, Agard DA Nat Commun. 2023 Feb 18;14(1):927. doi: 10.1038/s41467-023-36526-9. PMID:36807264[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
| ||||||||||||||||
