| Abstrakt: |
ABSTRACTThe histone deacetylase Rpd3p functions as a transcriptional repressor of a diverse set of genes, including PHO5. Here we describe a novel role for RPD3in the regulation of phosphate transporter Pho84p retention in the cytoplasmic membrane. We show that under repressing conditions (with Pi), PHO5expression is increased in a pho4? rpd3?strain, demonstrating PHOregulatory pathway independence. However, the effect of RPD3disruption on PHO5activation kinetics is dependent on the PHOregulatory pathway. Upon switching to activating conditions (without Pi), PHO5transcripts accumulated more rapidly in rpd3?cells. This more rapid response correlates with a defect in phosphate uptake due to premature recycling of Pho84p, the high-affinity H+/PO43-symporter. Thus, RPD3also participates in PHO5regulation through a previously unidentified effect on maintenance of high-affinity phosphate uptake during phosphate starvation. We propose that Rpd3p has a negative role in the regulation of Pho84p endocytosis. |
