Bacteriophage SPP1 connector-tail complex

Elena Orlova
Yuriy Chaban
Helen White
Paulo Tavares (CNRS, Gif sur Yvette, France)

Capsid structure of Bacteriophage SPP1 Assembly

Many icosahedral viruses use a specialized portal vertex for genome encapsidation and release from the viral capsid. After termination of encapsidation, the DNA packaging motor disassembles from the portal protein, a reaction tightly coordinated with closure of the portal system to avoid leakage of the viral genome. In tailed bacteriophages, this is most frequently achieved through binding of head completion proteins. The complex formed by the portal dodecamer and these proteins is named connector. The connector provides the interface for assembly of small tails in podoviruses and for attachment of sipho or myoviruses long tails. Structural and functional analyses suggest that both the portal protein and head completion proteins have conserved folds to accomplish their key roles retaining DNA inside the viral capsid, connecting to the tail device, and controlling its exit when genome ejection is triggered at the beginning of infection.Atomic models of gp6 (in blue), gp15 (dark red), gp16 (green) and gp17 (purple) are fitted by Flex-EM into the conneftor-tail cpmplex.

EM group web page Elena Orlova