The yeast 14-3-3 proteins BMH1 and BMH2 differentially regulate rapamycin-mediated transcription.

14-3-3 proteins are highly conserved and have been found in all eukaryotic organisms investigated. They are involved in many varied cellular processes, and interact with hundreds of other proteins. Among many other roles in cells, yeast 14-3-3 proteins have been implicated in rapamycin-mediated cell signalling. We determined the transcription profiles of bmh1 and bmh2 yeast after treatment with rapamycin. We found that, under these conditions, BMH1 and BMH2 are required for rapamycin-induced regulation of distinct, but overlapping sets of genes. Both Bmh1 and Bmh2 associate with the promoters of at least some of these genes. BMH2, but not BMH1, attenuates the repression of genes involved in some functions required for ribosome biogenesis. BMH2 also attenuates the activation of genes sensitive to nitrogen catabolite repression.

Comparative genome analysis suggests characteristics of yeast inverted repeats that are important for transcriptional activity.

Inverted repeats are sequences of DNA that, when read in the 5' to 3' direction, have the same sequence on both strands (palindromic portion), with the exception of a small number of nucleotides in the exact center (nonpalindromic spacer). They have been implicated in various DNA-mediated processes including replication, transcription, and genomic instability. At least some of these sequences are capable of forming an alternative DNA structure, called a cruciform, that may be important for mediating these functions. We generated a list of inverted repeats in the Saccharomyces cerevisiae genome and determined which of them are conserved in three related yeasts. We have identified characterisitics of inverted repeats that make them more likely to be conserved than the surrounding DNA and characteristics, such as position and base composition, that make the genes they are associated with likely to be more actively transcribed. This is an important step in determining the functions of this group of genomic elements.