Global Promoter Targeting of a Conserved Lysine Deacetylase for Transcriptional Shutoff during Quiescence Entry.

Quiescence is a conserved cell-cycle state characterized by cell-cycle arrest, increased stress resistance, enhanced longevity, and decreased transcriptional, translational, and metabolic output. Although quiescence plays essential roles in cell survival and normal differentiation, the molecular mechanisms leading to this state are not well understood. Here, we determined changes in the transcriptome and chromatin structure of S. cerevisiae upon quiescence entry. Our analyses revealed transcriptional shutoff that is far more robust than previously believed and an unprecedented global chromatin transition, which are tightly correlated. These changes require Rpd3 lysine deacetylase targeting to at least half of gene promoters via quiescence-specific transcription factors including Xbp1 and Stb3. Deletion of RPD3 prevents cells from establishing transcriptional quiescence, leading to defects in quiescence entry and shortening of chronological lifespan. Our results define a molecular mechanism for global reprogramming of transcriptome and chromatin structure for quiescence driven by a highly conserved chromatin regulator.

trans-Acetyl-dicarbon-yl(η(5)-cyclo-penta-dien-yl)(methyl-diphenyl-phosphane)molybdenum(II).

The title compound, [Mo(C(5)H(5))(C(2)H(3)O)(C(13)H(13)P)(CO)(2)], was prepared by reaction of [Mo(CH(3))(C(5)H(5))(CO)(3)] with methyl-diphenyl-phosphane. The Mo(II) atom exhibits a four-legged piano-stool coordination geometry with the acetyl and phosphane ligands trans to each other. There are several inter-molecular C-H⋯O hydrogen-bonding inter-actions involving carbonyl and acetyl O atoms as acceptors. A close nearly parallel π-π inter-action between the cyclo-penta-dienyl plane and the phenyl ring of the phosphane ligand is present, with an angle of 6.4 (1)° between the two least-squares planes. The centroid-to-centroid distance between these groups is 3.772 (3) Å, and the closest distance between two atoms of these groups is 3.449 (4) Å. Since each Mo complex is engaged in two of these inter-actions, the complexes form an infinite π-stack coincident with the a axis.