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Large icosahedral viruses and tailed bacteriophages encode a portal protein that assembles into a dodecameric ring and occupies one of the twelve five-fold-symmetric vertices of a viral capsid. This unique symmetry-mismatched and structurally conserved portal vertex is essential for head assembly, genome packaging, neck/tail attachment, and genome ejection, but the underlying mechanisms remain poorly understood. Here, we present evidence that the phage T4 portal functions as a global assembly communicator and signal transducer, with its basket-shaped channel containing twenty-four anti-parallel helices at its core. Disruption of a single inter-helical salt-bridge that connects helices in a circular brace impairs channel movements that might be essential for a DNA grip-release mechanism during genome translocation. Second and third site suppressors that compensate for this defect fall in distant portal and packaging motor domains that together form a sophisticated communication network. Such networks might underlie the structural frameworks of macromolecular assemblies in biological systems.