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J. Biol. Chem., Vol. 282, Issue 9, 6716-6725, March 2, 2007

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Activation of Multifarious Transcription of an Adhesion Protein ap65-1 Gene by a Novel Myb2 Protein in the Protozoan Parasite Trichomonas vaginalis^*

Shiou-Jeng Ong, Hong-Ming Hsu, Hsing-Wei Liu, Chien-Hsin Chu, and Jung-Hsiang Tai¹

From the Department of Parasitology, College of Medicine, National Taiwan University and the Division of Infectious Diseases, Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan

Multifarious transcription of the adhesion protein ap65-1 gene in the human pathogen, Trichomonas vaginalis, is critically regulated by the coordination of two similar but opposite oriented DNA regulatory regions, MRE-1/MRE-2r and MRE-2f, both of which are binding sites for multiple Myb-like proteins. In the present study, MRE-1/MRE-2r was demonstrated to be composed of multiple overlapping promoter elements, among which the entire region is required for growth-related ap65-1 transcription, and the 5'-MRE-1 antagonizes the suppressive activity of the 3'-MRE-2r in iron-inducible transcription. The recombinant Myb2 protein derived from a previously identified myb2 gene was demonstrated to recognize distinct sequence contexts in MRE-2r and MRE-2f, whereas Myb2 in the nuclear lysate preferentially binds to MRE-2f to MRE-2r. Iron repletion resulted in persistent repression of the myb2 gene, and temporal activation/deactivation of Myb2 promoter entry, which was also activated by prolonged iron depletion. The hemagglutinintagged Myb2 when overexpressed during iron-depleted conditions facilitated basal and growth-related ap65-1 transcription to a level that was achieved in iron-replete cells, whereas ironinducible ap65-1 transcription was abolished with knockdown of Myb2. These findings demonstrated that Myb2 is involved in activation of growth-related and iron-inducible transcription of the ap65-1 gene, possibly through differential promoter selection in competition with other Myb proteins.

Received for publication, November 10, 2006 , and in revised form, December 22, 2006.

^* This work was supported in part by Grants from the National Science Council (NSC92-2314-B-001-009 and NSC93-2314-B-001-003) and IBMS, Academia Sinica. 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 To whom correspondence should be addressed: Division of Infectious Diseases, Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan 11529. Tel.: 886-2-26523934; Fax: 886-2-27858847; E-mail: taijh{at}gate.sinica.edu.tw.

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				H.-M. Hsu, S.-J. Ong, M.-C. Lee, and J.-H. Tai Transcriptional Regulation of an Iron-Inducible Gene by Differential and Alternate Promoter Entries of Multiple Myb Proteins in the Protozoan Parasite Trichomonas vaginalis Eukaryot. Cell, March 1, 2009; 8(3): 362 - 372. [Abstract] [Full Text] [PDF]