Isolation of temperature sensitive mutants of Autographa californica nuclear polyhedrosis virus: Phenotype characterization of baculovirus mutants defective in very late gene expression

Virology ◽  
1990 ◽  
Vol 175 (1) ◽  
pp. 91-102 ◽  
Author(s):  
S. Partington ◽  
H. Yu ◽  
A. Lu ◽  
E.B. Carstens
Keyword(s):  
Gene Expression ◽  
Nuclear Polyhedrosis Virus ◽  
Autographa Californica ◽  
Late Gene ◽  
Temperature Sensitive ◽  
Late Gene Expression ◽  
Temperature Sensitive Mutants ◽  
Phenotype Characterization ◽  
Nuclear Polyhedrosis

scholarly journals The LEF-4 Subunit of Baculovirus RNA Polymerase Has RNA 5′-Triphosphatase and ATPase Activities

1998 ◽  
Vol 72 (12) ◽  
pp. 10011-10019 ◽  
Author(s):  
Jianping Jin ◽  
Wen Dong ◽  
Linda A. Guarino
Keyword(s):  
Rna Polymerase ◽  
Nuclear Polyhedrosis Virus ◽  
Autographa Californica ◽  
Temperature Sensitive ◽  
Late Gene Expression ◽  
Virus Rna ◽  
Rna Triphosphatase ◽  
Full Complement ◽  
Nuclear Polyhedrosis ◽  
Capping Enzymes

ABSTRACT The baculovirus Autographa californica nuclear polyhedrosis virus encodes a DNA-dependent RNA polymerase that is required for transcription of viral late genes. This polymerase is composed of four equimolar subunits, LEF-8, LEF-4, LEF-9, and p47. The LEF-4 subunit has guanylyltransferase activity, suggesting that baculoviruses may encode a full complement of capping enzymes. Here we show that LEF-4 is a bifunctional enzyme that hydrolyzes the gamma phosphates of triphosphate-terminated RNA and also hydrolyzes ATP and GTP to the respective diphosphate forms. Alanine substitution of five residues previously shown to be essential for vaccinia virus RNA triphosphatase activity inactivated the triphosphatase component of LEF-4 but not the guanylyltransferase domain. Conversely, mutation of the invariant lysine in the guanylyltransferase domain abolished the guanylyltransferase activity without affecting triphosphatase function. We also investigated the effects of substituting phenylalanine for leucine at position 105, a mutation that results in a virus that is temperature sensitive for late gene expression. We found that this mutation had no significant effect on the ATPase or guanylyltransferase activity of LEF-4 but resulted in a modest decrease in RNA triphosphatase activity.

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