A maltose-binding protein/adeno-associated virus Rep68 fusion protein has DNA-RNA helicase and ATPase activities
Abstract
The adeno-associated virus type 2 (AAV) Rep68 protein produced in Escherichia coli as a fusion protein with maltose-binding protein (MBP-Rep68 delta) has previously been shown to possess DNA-DNA helicase activity, as does the purified wild-type Rep68. In the present study, we demonstrate that MBP-Rep68 delta also catalyzes the unwinding of a DNA-RNA hybrid. MBP-Rep68 delta-mediated DNA-RNA helicase activity required ATP hydrolysis and the presence of Mg2+ ions and was inhibited by high ionic strength. The efficiency of the DNA-RNA helicase activity of MBP-Rep68 delta was comparable to its DNA-DNA helicase activity. However, MBP-Rep68 delta lacked the ability to unwind a blunt-ended DNA-RNA substrate and RNA-RNA duplexes. We have also demonstrated that MBP-Rep68 delta has ATPase activity which is enhanced by the presence of single-stranded DNA but not by RNA. The MBP-Rep68 delta NTP mutant protein, which has a lysine-to-histidine substitution at amino acid 340 in the putative nucleoside triphosphate-binding site of Rep68, not only lacks DNA-RNA helicase and ATPase activities but also inhibits the helicase activity of MBP-Rep68 delta. DNA-RNA helicase activity of Rep proteins might play a pivotal role in the regulation of AAV gen...Continue Reading
References
Mutagenesis of an AUG codon in the adeno-associated virus rep gene: effects on viral DNA replication
Identification of linear DNA sequences that specifically bind the adeno-associated virus Rep protein
Citations
The helicase domain of the TMV replicase proteins induces the N-mediated defence response in tobacco
Analysis of the effects of charge cluster mutations in adeno-associated virus Rep68 protein in vitro
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