TY - JOUR
T1 - Identification of the point mutations in two vaccinia virus nucleoside triphosphate phosphohydrolase I temperature-sensitive mutants and role of this DNA-dependent ATPase enzyme in virus gene expression
AU - Kahn, Jeffrey
AU - Esteban, Mariano
PY - 1990/2
Y1 - 1990/2
N2 - The biological function of the nucleoside triphosphate phosphohydrolase I (NTPase I) enzyme of vaccinia virus is not yet known. In this investigation we have identified the genetic lesion of two temperature-sensitive mutants of vaccinia virus, ts50 and ts36, as single point mutations contained within the 5'615 nucleotides of the NTPase I gene (ts50, G to A at position 131; ts36, C to T at position 556). The point mutations result in amino acid substitutions of Gly to Glu-44 (ts50) and Pro to Ser-186 (ts36). In monkey BSC-40 cells, ts50 and ts36 behave phenotypically like wild-type virus with respect to replication and synthesis of viral DNA but are defective in late polypeptide synthesis. However, these two ts mutants displayed a drastically different phenotype in virus-infected human HeLa cells at the restrictive temperature; viral DNA replication did not occur and late polypeptide synthesis was absent. Moreover, if the early block was overcome by a temperature shift-up, then HeLa cells infected with the is mutants displayed a profile characteristic of defective late viral polypeptide synthesis. Our results reveal that vaccinia NTPase I enzyme functions early and late in the viral replication cycle and that the phenotype of these is mutants is dependent upon the cell type.
AB - The biological function of the nucleoside triphosphate phosphohydrolase I (NTPase I) enzyme of vaccinia virus is not yet known. In this investigation we have identified the genetic lesion of two temperature-sensitive mutants of vaccinia virus, ts50 and ts36, as single point mutations contained within the 5'615 nucleotides of the NTPase I gene (ts50, G to A at position 131; ts36, C to T at position 556). The point mutations result in amino acid substitutions of Gly to Glu-44 (ts50) and Pro to Ser-186 (ts36). In monkey BSC-40 cells, ts50 and ts36 behave phenotypically like wild-type virus with respect to replication and synthesis of viral DNA but are defective in late polypeptide synthesis. However, these two ts mutants displayed a drastically different phenotype in virus-infected human HeLa cells at the restrictive temperature; viral DNA replication did not occur and late polypeptide synthesis was absent. Moreover, if the early block was overcome by a temperature shift-up, then HeLa cells infected with the is mutants displayed a profile characteristic of defective late viral polypeptide synthesis. Our results reveal that vaccinia NTPase I enzyme functions early and late in the viral replication cycle and that the phenotype of these is mutants is dependent upon the cell type.
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U2 - 10.1016/0042-6822(90)90100-6
DO - 10.1016/0042-6822(90)90100-6
M3 - Article
C2 - 2154883
AN - SCOPUS:0025064270
SN - 0042-6822
VL - 174
SP - 459
EP - 471
JO - Virology
JF - Virology
IS - 2
ER -