A genome-wide analysis of transcriptional effect of Gal11 in Saccharomyces cerevisiae: an application of "mini-array hybridization technique".

The Gal11 protein is a subunit of the Mediator complex. Biochemical as well as genetic studies have strongly suggested that Gal11 is a positive global regulator of transcription. Some reports argue that Gal11 is a negative regulator, however. Here we have adopted the "Mini-array membrane hybridization" to analyze the effect of Gal11 in a genome-wide fashion. This technique has been demonstrated to be reliable to identify genes whose expression is controlled by a specific set of genetic and/or physiological signals. Our experiments indicate that this technique is applicable to profile the gene expression in yeast grown in rich medium. Thus mRNAs of 40% of significantly expressed genes are reduced more than two fold in gal11null yeast, in which only 3% of mRNAs are increased more than two fold. These results strongly suggest that Gal11 functions globally as a positive regulator in vivo.