在酿酒酵母中,Rpd3L复合物含有组蛋白脱乙酰酶,Rpd3和DNA结合蛋白,Ume6和Ash1,并充当转录阻遏子或激活子。我们以前表明,RPD3和UME6是PDR5的激活所必需的,PDR5编码一个主要的外排泵,和ρ0/-细胞的多效性耐药性(PDR),缺乏线粒体DNA。然而,关于线粒体DNA的ρ+细胞中Pdr5介导的PDR是否需要RPD3和UME6的报道不一致。由于已经主要使用可发酵培养基检查了rpd3Δ和ume6Δ突变体的ρ细胞中的PDR5表达或PDR,可以使用ρ+和ρ0/-细胞的混合培养物。因此,我们使用可发酵和不可发酵培养基检查了ρ+细胞中基础和药物诱导的PDR5转录和PDR是否需要RPD3和UME6。UME6抑制ABC转运蛋白的基础转录水平,包括PDR5和ρ+细胞中的耐药性,而与生长培养基中使用的碳源无关。相比之下,RPD3是耐药性所必需的,但不干扰基础PDR5mRNA水平。UME6也是环己酰亚胺诱导的PDR5在不可发酵培养基中的转录所必需的,而不是在可发酵培养基中。
In Saccharomycescerevisiae, the Rpd3L complex contains a histone deacetylase, Rpd3, and the DNA binding proteins,
Ume6 and Ash1, and acts as a transcriptional repressor or activator. We previously showed that RPD3 and
UME6 are required for the activation of PDR5, which encodes a major efflux pump, and pleiotropic drug resistance (PDR) in ρ0/- cells, which lack mitochondrial DNA. However, there are inconsistent reports regarding whether RPD3 and
UME6 are required for Pdr5-mediated PDR in ρ+ cells with mitochondrial DNA. Since PDR5 expression or PDR in the ρ+ cells of the rpd3Δ and ume6Δ mutants have primarily been examined using fermentable media, mixed cultures of ρ+ and ρ0/- cells could be used. Therefore, we examined whether RPD3 and
UME6 are required for basal and drug-induced PDR5 transcription and PDR in ρ+ cells using fermentable and nonfermentable media. UME6 suppresses the basal transcription levels of the ABC transporters, including PDR5, and drug resistance in ρ+ cells independent of the carbon source used in the growth medium. In contrast, RPD3 is required for drug resistance but did not interfere with the basal PDR5 mRNA levels.
UME6 is also required for the cycloheximide-induced transcription of PDR5 in nonfermentable media but not in fermentable media.