C-terminal Trimerization, but Not N-terminal Trimerization, of the Reovirus Cell Attachment Protein Is a Posttranslational and Hsp70/ATP-dependent Process

• Published in: The Journal of biological chemistry Vol. 271; no. 14; pp. 8466 - 8471
• Main Authors: Leone, G, Coffey, M C, Gilmore, R, Duncan, R, Maybaum, L, Lee, P W
• Format: Journal Article
• Language: English
• Published: United States American Society for Biochemistry and Molecular Biology 05-04-1996
• Subjects: Adenosine Triphosphate - metabolism; Animals; Capsid Proteins; Cell-Free System; HSP70 Heat-Shock Proteins - metabolism; Macromolecular Substances; Molecular Chaperones - metabolism; Protein Binding; Protein Biosynthesis; Protein Folding; Protein Processing, Post-Translational; Rabbits; Receptors, Virus - metabolism; rotavirus; Sequence Deletion; Structure-Activity Relationship; Viral Proteins - chemistry; Viral Proteins - metabolism
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.271.14.8466

The C-terminal globular head of the lollipop-shaped 1 protein of reovirus is responsible for interaction with the host cell receptor. Like the N-terminal fibrous tail, it has
its own trimerization domain. Whereas N-terminal trimerization (formation of a triple α-helical coiled coil) occurs at the
level of polysomes (i.e. cotranslationally) and is ATP-independent, C-terminal trimerization is a posttranslational event
that requires ATP. Coprecipitation experiments using anti-Hsp70 antibodies and truncated 1 proteins synthesized in vitro revealed that only regions downstream of the N-terminal α-helical coiled coil were associated with Hsp70. Hsp70 was also
found to be associated with nascent 1 chains on polysomes as well as with immature postribosomal 1 trimers (hydra-like intermediates with assembled N termini and unassembled C termini). These latter structures were true
intermediates in the 1 biogenetic pathway since they could be chased into mature 1 trimers with the release of Hsp70. Thus, unlike N-terminal trimerization, C-terminal trimerization is Hsp70- and ATP-dependent.
The involvement of two mechanistically distinct oligomerization events for the same molecule, one cotranslational and one
posttranslational, may represent a common approach to the generation of oligomeric proteins in the cytosol.