Dbp9p, a Member of the DEAD Box Protein Family, Exhibits DNA Helicase Activity

The yeast Dbp9p is a member of the DEAD box family of RNA helicases, which are thought to be involved in RNA metabolism. Dbp9p seems to function in ribosomal RNA biogenesis, but it has not been biochemically characterized. To analyze the enzymatic characteristics of the protein, we expressed a recom...

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Bibliographic Details
Published in:	The Journal of biological chemistry Vol. 279; no. 20; pp. 20692 - 20698
Main Authors:	Kikuma, Takashi, Ohtsu, Masaya, Utsugi, Takahiko, Koga, Shoko, Okuhara, Kohji, Eki, Toshihiko, Fujimori, Fumihiro, Murakami, Yasufumi
Format:	Journal Article
Language:	English
Published:	United States American Society for Biochemistry and Molecular Biology 14-05-2004
Subjects:	Adenosine Triphosphatases - metabolism Base Sequence DEAD-box RNA Helicases DNA Helicases - isolation & purification DNA Helicases - metabolism DNA, Fungal - chemistry DNA, Fungal - genetics DNA, Fungal - metabolism DNA, Single-Stranded - drug effects DNA, Single-Stranded - metabolism Kinetics Nuclear Proteins - isolation & purification Nuclear Proteins - metabolism RNA Helicases - isolation & purification RNA Helicases - metabolism RNA, Fungal - metabolism Saccharomyces cerevisiae Saccharomyces cerevisiae - enzymology Saccharomyces cerevisiae - genetics Saccharomyces cerevisiae Proteins - isolation & purification Saccharomyces cerevisiae Proteins - metabolism
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Summary:	The yeast Dbp9p is a member of the DEAD box family of RNA helicases, which are thought to be involved in RNA metabolism. Dbp9p seems to function in ribosomal RNA biogenesis, but it has not been biochemically characterized. To analyze the enzymatic characteristics of the protein, we expressed a recombinant Dbp9p in Escherichia coli and purified it to homogeneity. The purified protein exhibited RNA unwinding and binding activity in the absence of NTP, and this activity was abolished by a mutation in the RNA-binding domain. We then characterized the ATPase activity of Dbp9p with respect to cofactor specificity; the activity was found to be severely inhibited by yeast total RNA and moderately inhibited by poly(U), poly(A), and poly(C) but to be stimulated by yeast genomic DNA and salmon sperm DNA. In addition, Dbp9p exhibited DNA-DNA and DNA-RNA helicase activity in the presence of ATP. These results indicate that Dbp9p has biochemical characteristics unique among DEAD box proteins.
Bibliography:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23
ISSN:	0021-9258 1083-351X
DOI:	10.1074/jbc.M400231200