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J. Biol. Chem., Vol. 282, Issue 24, 17507-17516, June 15, 2007
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12
1
¶
3
From the
Basic Research Laboratory,
Laboratory of Metabolism, Center for Cancer Research, NCI, and ¶Pharmacology Research Associate Program, NIGMS, National Institutes of Health, Bethesda, Maryland 20892
Mammalian UAP56 or its homolog Sub2p in Saccharomyces cerevisiae are members of the ATP-dependent RNA helicase family and are required for splicing and nuclear export of mRNA. Previously we showed that in Schizosaccharomyces pombe Uap56p is critical for mRNA export. It links the mRNA adapter Mlo3p, a homolog of Yra1p in S. cerevisiae or Aly in mammals, to nuclear pore-associated mRNA export factor Rae1p. In this study we show that, in contrast to S. cerevisiae, Uap56p in S. pombe is not required for pre-mRNA splicing. The putative RNA helicase function of Uap56p is not required for mRNA export. However, the RNA-binding motif of Uap56p is critical for nuclear export of mRNA. Within Uap56p we identified nuclear import and export signals that may allow it to shuttle between the nucleus and the cytoplasm. We found that Uap56p interacts with Rae1p directly via its nuclear export signal, and this interaction is critical for the nuclear export activity of Uap56p as well as for exporting mRNA. RNA binding and the ability to shuttle between the nucleus and cytoplasm are important features of mRNA export carriers such as HIV-Rev. Our results suggest that Uap56p could function similarly as an export carrier of mRNA in S. pombe.
Received for publication, October 16, 2006 , and in revised form, April 20, 2007.
* This work was supported by the Center for Cancer Research, the intramural program of the NCI, National Institutes of Health. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
1 Both authors contributed equally to this work.
2 Present address: AstraZeneca Pharmaceuticals, 1700 Auburn Ave., Rockville, MD 20850.
3 To whom correspondence should be addressed: Basic Research Laboratory, Center for Cancer Research, NCI, National Institutes of Health, Bldg. 37, Rm. 5016, 37 Convent Dr., 9000 Rockville Pike, Bethesda, MD 20892. Tel.: 301-496-0990; Fax: 301-480-5088; E-mail: dharr{at}mail.nih.gov.
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