A Structural Basis for the Assembly and Functions of a Viral Polymer that Inactivates Multiple Tumor Suppressors

SummaryEvolution of minimal DNA tumor virus' genomes has selected for small viral oncoproteins that hijack critical cellular protein interaction networks. The structural basis for the multiple and dominant functions of adenovirus oncoproteins has remained elusive. E4-ORF3 forms a nuclear polymer and simultaneously inactivates p53, PML, TRIM24, and MRE11/RAD50/NBS1 (MRN) tumor suppressors. We identify oligomerization mutants and solve the crystal structure of E4-ORF3. E4-ORF3 forms a dimer with a central β core, and its structure is unrelated to known polymers or oncogenes. E4-ORF3 dimer units coassemble through reciprocal and nonreciprocal exchanges of their C-terminal tails. This results in linear and branched oligomer chains that further assemble in variable arrangements to form a polymer network that partitions the nuclear volume. E4-ORF3 assembly creates avidity-driven interactions with PML and an emergent MRN binding interface. This reveals an elegant structural solution whereby a small protein forms a multivalent matrix that traps disparate tumor suppressors.PaperFlick To view the video inline, enable JavaScript on your browser. However, you can download and view the video by clicking on the icon belowHelp with MP4 filesOptionsDownload video (20561 K)

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► Crystal structure of the adenovirus oncoprotein E4-ORF3 reveals a dimer subunit
► E4-ORF3 dimers coassemble in multiple configurations by exchanging C-terminal tails
► E4-ORF3 polymers are disordered weaves of linear and branched oligomer chains
► E4-ORF3 forms an emergent multivalent interaction matrix that captures PML and MRN