Analysis of Ad5 hexon and 100K ts mutants using conformation-specific monoclonal antibodies.

Adenovirus type 5 ts mutants deficient in hexon metabolism were investigated using conformation-specific monoclonal antibodies directed against hexon capsomeres and the viral 100K protein. The ts mutants map either in the hexon structural gene or in the gene encoding the 100K protein, a major, late nonstructural protein. All of the mutants examined (ts1, ts2, ts3, ts4, ts17, and ts20 of J. F. Williams, M. Gharpure, S. Ustacelebi, and S. McDonald (1971). J. Gen. Virol. 11, 95-101) were unable to produce the capsomeric form of hexon (a trimer of three hexon monomers) at the nonpermissive temperature. However, all of the mutants retained the ability to produce a complex of 100K and hexon which has been demonstrated to play a major role in the assembly of hexon trimers. The mutants accumulated nontrimerized hexon in this ts complex in the perinuclear region of the cell. Several of the mutants (ts1, ts2, ts3) were found to successfully assemble hexon synthesized at the nonpermissive temperature upon shift down to the permissive temperature, even in the presence of a protein synthesis inhibitor. The mutant, ts2, which maps in the hexon structural gene, was found to be dependent on protein synthesis for transport of hexon trimers into the nucleus during temperature shift down, while the 100K ts mutants, ts1 and ts3, were independent of protein synthesis for both hexon assembly and transport.