title: 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.
abstract: 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.
authors.affiliation: Departement de Biochimie Médicale, Centre Médical Universitaire, Université de Genève, Geneva, Switzerland. William.Kelley@medecine.unige.ch
authors.forename: W L
authors.initials: WL
authors.lastname: Kelley
authors.forename: C
authors.initials: C
authors.lastname: Georgopoulos
mesh_terms: D000595:Amino Acid Sequence; D000957:Antigens, Viral, Tumor / Q000235:genetics*; D001739:BK Virus / Q000235:genetics* / Q000276:immunology; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins; D005091:Exons / Q000235:genetics*; D050956:HSP40 Heat-Shock Proteins; D006360:Heat-Shock Proteins / Q000235:genetics*; D007577:JC Virus / Q000235:genetics* / Q000276:immunology; D008969:Molecular Sequence Data; D016415:Sequence Alignment; D017421:Sequence Analysis; D013539:Simian virus 40 / Q000235:genetics* / Q000276:immunology
chemical_list: D000957:Antigens, Viral, Tumor; C494635:DnaJ protein, E coli; D029968:Escherichia coli Proteins; D050956:HSP40 Heat-Shock Proteins; D006360:Heat-Shock Proteins