This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by McNabb, D. S. Articles by Pinto, I. Search for Related Content PubMed PubMed Citation Articles by McNabb, D. S. Articles by Pinto, I.

Assembly of the Hap2p/Hap3p/Hap4p/Hap5p-DNA Complex in Saccharomyces cerevisiae

Department of Biological Sciences, University of Arkansas, Fayetteville, Arkansas 72701

Received 30 July 2005/ Accepted 25 August 2005

The CCAAT-binding factor (CBF) is an evolutionarily conserved multimeric transcriptional activator in eukaryotes. In Saccharomyces cerevisiae, the CCAAT-binding factor is composed of four subunits, termed Hap2p, Hap3p, Hap4p, and Hap5p. The Hap2p/Hap3p/Hap5p heterotrimer is the DNA-binding component of the complex that binds to the consensus 5'-CCAAT-3' sequence in the promoter of target genes. The Hap4p subunit contains the transcriptional activation domain necessary for stimulating transcription after interacting with Hap2p/Hap3p/Hap5p. In this report, we demonstrate that Hap2p, Hap3p, and Hap5p assemble via a one-step pathway requiring all three subunits simultaneously, as opposed to the mammalian CCAAT-binding factor which has been shown to assemble via a two-step pathway with CBF-A (Hap3p homolog) and CBF-C (Hap5p homolog) forming a stable dimer before CBF-B (Hap2p homolog) can interact. We have also found that the interaction of Hap4p with Hap2p/Hap3p/Hap5p requires DNA binding as a prerequisite. To further understand the protein-protein and protein-DNA interactions of this transcription factor, we identified the minimal domain of Hap4p necessary for interaction with the Hap2p/Hap3p/Hap5p-DNA complex, and we demonstrate that this domain is sufficient to complement the respiratory deficiency of a hap4 mutant and activate transcription when fused with the VP16 activation domain. These studies provide a further understanding of the assembly of the yeast CCAAT-binding factor at target promoters and raise a number of questions concerning the protein-protein and protein-DNA interactions of this multisubunit transcription factor.

This article has been cited by other articles:

• Fontanesi, F., Jin, C., Tzagoloff, A., Barrientos, A. (2008). Transcriptional activators HAP/NF-Y rescue a cytochrome c oxidase defect in yeast and human cells. Hum Mol Genet 17: 775-788 [Abstract] [Full Text]  
• Mercier, A., Watt, S., Bahler, J., Labbe, S. (2008). Key Function for the CCAAT-Binding Factor Php4 To Regulate Gene Expression in Response to Iron Deficiency in Fission Yeast. Eukaryot Cell 7: 493-508 [Abstract] [Full Text]  
• Etxebeste, O., Ni, M., Garzia, A., Kwon, N.-J., Fischer, R., Yu, J.-H., Espeso, E. A., Ugalde, U. (2008). Basic-Zipper-Type Transcription Factor FlbB Controls Asexual Development in Aspergillus nidulans. Eukaryot Cell 7: 38-48 [Abstract] [Full Text]  
• Fontanesi, F., Soto, I. C., Horn, D., Barrientos, A. (2006). Assembly of mitochondrial cytochrome c-oxidase, a complicated and highly regulated cellular process. Am. J. Physiol. Cell Physiol. 291: C1129-C1147 [Abstract] [Full Text]  
• Mercier, A., Pelletier, B., Labbe, S. (2006). A Transcription Factor Cascade Involving Fep1 and the CCAAT-Binding Factor Php4 Regulates Gene Expression in Response to Iron Deficiency in the Fission Yeast Schizosaccharomyces pombe. Eukaryot Cell 5: 1866-1881 [Abstract] [Full Text]  
• Wenkel, S., Turck, F., Singer, K., Gissot, L., Le Gourrierec, J., Samach, A., Coupland, G. (2006). CONSTANS and the CCAAT Box Binding Complex Share a Functionally Important Domain and Interact to Regulate Flowering of Arabidopsis. Plant Cell 18: 2971-2984 [Abstract] [Full Text]