A mutation in the adenovirus type 5 DNA binding protein that fails to autoregulate the production of the dna binding protein

Abstract

H5ts125 is a temperature-sensitive mutant of type 5 adenovirus whose defect maps in the structural gene of the viral DNA binding protein. Among a large number of temperature-independent revertants of this mutant, that plaque efficiently at 39° in HeLa cells, one revertant, r(ts125)13, has been studied in more detail. The synthesis and stability of the adenovirus DNA binding protein in HeLa cells infected with Ad5wt, H5ts125, and r(ts125)13 was investigated by pulse-chase experiments with [ 35S]methionine. In H5ts125-infected cells at the nonpermissive temperature about 1 1 2 to 2 1 2 - fold more DNA binding protein was synthesized in the pulse-labeling period than was detected in wild-type infected cells. Unlike the wild-type protein, the H5ts125 DNA binding protein was unstable and it was degraded during the chase period. In r13-infected HeLa cells, the DNA binding protein was overproduced 3- to 5-fold during the pulse-labeling time. The r13 DNA binding protein was stable and accumulated throughout the chase period. The r13 DNA binding protein was not overproduced and remained stable during a chase period, in human 293 cells on monkey CV-1 cells indicating that the faulty autoregulation of the r13 DNA binding protein synthesis was host cell or host range specific. These experiments provide genetic evidence for the adenovirus DNA binding proteins' ability to autoregulate its own synthesis. In addition the results suggest that cellular functions, interacting with the DNA binding protein, play a role in this autoregulatory event.