Open AccessRNA 5′-Triphosphatase Activity of the Hepatitis E Virus Helicase Domain
Author(s) -
Yogesh A. Karpe,
Kavita S. Lole
Publication year - 2010
Publication title -
journal of virology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.617
H-Index - 292
eISSN - 1070-6321
pISSN - 0022-538X
DOI - 10.1128/jvi.00492-10
Subject(s) - rna helicase a , biology , helicase , rna , rna dependent rna polymerase , nucleoside triphosphate , triphosphatase , virology , open reading frame , hepatitis e virus , microbiology and biotechnology , biochemistry , enzyme , nucleotide , gene , peptide sequence , genotype
Hepatitis E virus (HEV) has a positive-sense RNA genome with a 5′-m7G cap. HEV open reading frame 1 (ORF1) encodes a polyprotein with multiple enzyme domains required for replication. HEV helicase is a nucleoside triphosphatase (NTPase) with the ability to unwind RNA duplexes in the 5′-to-3′ direction. When incubated with 5′-[γ-32 P]RNA and 5′-[α-32 P]RNA, HEV helicase released32 P only from 5′-[γ-32 P]RNA, showing specificity for the γ-β-triphosphate bond. Removal of γ-phosphate from the 5′ end of the primary transcripts (pppRNA to ppRNA) by RNA triphosphatase is an essential step during cap formation. It is suggested that HEV employs the helicase to mediate the first step of 5′ cap synthesis.