The T/t common exon of simian virus 40, JC, and BK polyomavirus T antigens can functionally replace the J-domain of the Escherichia coli DnaJ molecular chaperone

Proc Natl Acad Sci U S A. 1997 Apr 15;94(8):3679-84. doi: 10.1073/pnas.94.8.3679.


The N-terminal 70 residue "J-domain" of the Escherichia coli DnaJ molecular chaperone is the defining and highly conserved feature of a large protein family. Based upon limited, yet significant, amino acid sequence homology to the J-domain, the DNA encoding the T/t common exon of the simian virus 40 (SV40), JC, or BK polyoma virus T antigen oncoproteins was used to construct J-domain replacement chimeras of the E. coli DnaJ chaperone. The virally encoded J-domains successfully substituted for the bacterial counterpart in vivo as shown by (i) complementation for viability at low and high temperature of a hypersensitive bacterial reporter strain, and (ii) the restoration of bacteriophage lambda plaque forming ability in the same strain. The amino acid change, H42Q, in the SV40 T/t and the JC virus T/t exon, which is positionally equivalent to the canonical dnaJ259 H33Q mutation within the E. coli J-domain, entirely abolished complementing activity. These results strongly suggest that the heretofore functionally undefined viral T/t common exon represents a bona fide J-domain that preserves critical features of the characteristic domain fold essential for J-domain interaction with the ATPase domain of the Hsp70 family. This finding has implications for the regulation of DNA tumor virus T antigens by molecular chaperones.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Antigens, Viral, Tumor / genetics*
  • BK Virus / genetics*
  • BK Virus / immunology
  • Escherichia coli / genetics*
  • Escherichia coli Proteins
  • Exons / genetics*
  • HSP40 Heat-Shock Proteins
  • Heat-Shock Proteins / genetics*
  • JC Virus / genetics*
  • JC Virus / immunology
  • Molecular Sequence Data
  • Sequence Alignment
  • Sequence Analysis
  • Simian virus 40 / genetics*
  • Simian virus 40 / immunology


  • Antigens, Viral, Tumor
  • DnaJ protein, E coli
  • Escherichia coli Proteins
  • HSP40 Heat-Shock Proteins
  • Heat-Shock Proteins