The UGA3-GLT1 intergenic region constitutes a promoter whose bidirectional nature is determined by chromatin organization in Saccharomyces cerevisiae

Authors

  • Cecilia Ishida,

    1. Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Apartado Postal 70-242, 04510 México D. F., México.
    2. Departamento de Biología Celular, CINVESTAV-IPN, México D. F., México.
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  • Cristina Aranda,

    1. Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Apartado Postal 70-242, 04510 México D. F., México.
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  • Lourdes Valenzuela,

    1. Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Apartado Postal 70-242, 04510 México D. F., México.
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  • Lina Riego,

    1. Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Apartado Postal 70-242, 04510 México D. F., México.
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    • Present address: Instituto Potosino de Investigación Científica y Tecnológica, 78216 San Luis Potosí, México.

  • Alexander DeLuna,

    1. Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Apartado Postal 70-242, 04510 México D. F., México.
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  • Félix Recillas-Targa,

    1. Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Apartado Postal 70-242, 04510 México D. F., México.
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  • Patrizia Filetici,

    1. Istituto di Biología e Patología Molecolari, CNR, Universitá di Roma ‘La Sapienza’, P. Le Aldo Moro 5, Rome, 00185, Italy.
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  • Rubén López-Revilla,

    1. Departamento de Biología Celular, CINVESTAV-IPN, México D. F., México.
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    • Present address: Instituto Potosino de Investigación Científica y Tecnológica, 78216 San Luis Potosí, México.

  • Alicia González

    Corresponding author
    1. Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Apartado Postal 70-242, 04510 México D. F., México.
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*E-mail amanjarr@ifc.unam.mx; Tel. (+52) 555 622 5631; Fax (+52) 555 622 5630.

Summary

Transcription of an important number of divergent genes of Saccharomyces cerevisiae is controlled by intergenic regions, which constitute factual bidirectional promoters. However, few of such promoters have been characterized in detail. The analysis of the UGA3-GLT1 intergenic region has provided an interesting model to study the joint action of two global transcriptional activators that had been considered to act independently. Our results show that Gln3p and Gcn4p exert their effect upon cis-acting elements, which are shared in a bidirectional promoter. Accordingly, when yeast is grown on a low-quality nitrogen source, or under amino acid deprivation, the expression of both UGA3 and GLT1 is induced through the action of both these global transcriptional modulators that bind to a region of the bidirectional promoter. In addition, we demonstrate that chromatin organization plays a major role in the bidirectional properties of the UGA3-GLT1 promoter, through the action of an upstream Abf1p-binding consensus sequence and a polydAdTtract. Mutations in these cis-elements differentially affect transcription of UGA3 and GLT1, and thus alter the overall relative expression. This is the first example of an intergenic region constituting a promoter whose bidirectional character is determined by chromatin organization.

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