The transcription factor Pap1/Caf3 plays a central role in the determination of caffeine resistance in Schizosaccharomyces pombe
The transcription factor Pap1/Caf3 plays a central role in the determination of caffeine resistance in Schizosaccharomyces pombe
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DOI：
10.1007/s00438-003-0967-3
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发表时间：
2004-03-01
影响因子：
3.1
通讯作者：
Sipiczki, M
中科院分区：
文献类型：
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作者：
Benko, Z;Fenyvesvolgyi, C;Sipiczki, M
我们之前在Schizosaccharomyces pombe中鉴定了四个核基因(caf1(+)- caf4(+))，这些基因突变赋予了对咖啡因和brefeldin a的抗性，caf1(+), caf2（+）和caf4（+）的测序发现它们分别与多药耐药/应激反应基因hba1， crm1和trr1相同。本研究表明，caf3与编码ap -1样转录因子的pap1是等位基因。与咖啡因抗性相关的等位基因caf3-89包含一个单核苷酸交换，导致基因产物NES（核输出信号）区域的Leu- >Ser交换。由于这种改变，修饰后的蛋白质不能从细胞核输出到细胞质中，从而在细胞核中积累。pap1/caf3的活性被证明是hba1/caf1和crm1/caf2基因突变引起的咖啡因抗性表现所必需的。我们还克隆了两个在多拷贝质粒上携带时赋予咖啡因抗性的基因。其中一个是pad1/bfr2/sks1的截断等位基因，该基因编码26s蛋白体的一个亚基。另一个基因的推定产物，被称为caf5，具有与MFS permeases高度相似的结构。它包含两组6个跨膜结构域，其中保守基序WRW、PET和GAIGGPVLGP分别位于第五和第六结构域。这些结果都与我们之前的假设一致，即caf基因在复杂的解毒机制中具有功能上的相互联系。Caf5和pad1也可能编码该机制的一部分。
We previously identified four nuclear genes (caf1(+)- caf4(+)) in Schizosaccharomyces pombe, mutations in which confer resistance to caffeine and brefeldin A. caf1(+), caf2(+) and caf4(+) were sequenced and found to be identical to the multidrug-resistance/stress-response genes hba1, crm1 and trr1, respectively. Here we show that caf3 is allelic to pap1, which encodes an AP-1-like transcription factor. The allele associated with caffeine resistance, caf3-89 , contains a single-nucleotide exchange that results in a Leu-->Ser exchange in the NES (nuclear export signal) domain of the gene product. Due to this alteration, the modified protein can not be exported from the nucleus back into the cytoplasm, and thus accumulates in the nucleus. The activity of pap1/caf3 is shown to be necessary for manifestation of the caffeine resistance caused by mutations in the genes hba1/caf1 and crm1/caf2. We also cloned two genes that confer caffeine resistance when carried on a multicopy plasmid. One of them turned out to be a truncated allele of pad1/bfr2/sks1, which codes for a subunit of the 26 S proteosome. The putative product of the other gene, designated caf5, has a structure highly similar to that of MFS permeases. It contains two groups of six transmembrane spanning domains each, with the conserved motifs WRW, PET and GAIGGPVLGP in the fifth and sixth domains. These results are all consistent with our earlier hypothesis, which suggested that the caf genes are functionally interlinked in a complex detoxification mechanism. caf5 and pad1 may also encode parts of this mechanism.