7k5c
From Proteopedia
Structure of T7 DNA ejectosome periplasmic tunnel
Structural highlights
FunctionGP15_BPT7 Component of the cylindrical core that assembles on the inner surface of the capsid during capsid formation and plays a role in viral DNA ejection into the host cell. The inner core is composed of stacked rings of gp14, gp15 and gp16 proteins. Following binding to the host cell surface, the internal core is disassembled and gp15 is ejected along with gp14 and gp16 into the infected cell. Gp15 probably remains associated with gp16. The gp15-gp16 complex binds to both the viral DNA and the host inner membrane, probably escorting the leading end of the genome through the periplasm and controlling the extend of DNA translocated into the host cell.[HAMAP-Rule:MF_04122][1] [2] Publication Abstract from PubMedHershey and Chase used bacteriophage T2 genome delivery inside Escherichia coli to demonstrate that DNA, not protein, is the genetic material. Seventy years later, our understanding of viral genome delivery in prokaryotes remains limited, especially for short-tailed phages of the Podoviridae family. These viruses expel mysterious ejection proteins found inside the capsid to form a DNA-ejectosome for genome delivery into bacteria. Here, we reconstitute the phage T7 DNA-ejectosome components gp14, gp15, and gp16 and solve the periplasmic tunnel structure at 2.7 A resolution. We find that gp14 forms an outer membrane pore, gp15 assembles into a 210 A hexameric DNA tube spanning the host periplasm, and gp16 extends into the host cytoplasm forming a approximately 4,200 residue hub. Gp16 promotes gp15 oligomerization, coordinating peptidoglycan hydrolysis, DNA binding, and lipid insertion. The reconstituted gp15:gp16 complex lacks channel-forming activity, suggesting that the pore for DNA passage forms only transiently during genome ejection. Cryo-EM structure of the periplasmic tunnel of T7 DNA-ejectosome at 2.7 A resolution.,Swanson NA, Lokareddy RK, Li F, Hou CD, Leptihn S, Pavlenok M, Niederweis M, Pumroy RA, Moiseenkova-Bell VY, Cingolani G Mol Cell. 2021 Aug 5;81(15):3145-3159.e7. doi: 10.1016/j.molcel.2021.06.001. Epub , 2021 Jul 1. PMID:34214465[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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