Strich R, Surosky R T, Steber C, Dubois E, Messenguy F, Esposito R E
Institute for Cancer Research, Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111.
Genes Dev. 1994 Apr 1;8(7):796-810. doi: 10.1101/gad.8.7.796.
This report describes the identification, cloning, and molecular analysis of UME6 (CAR80/CARGRI), a key transcriptional regulator of early meiotic gene expression. Loss of UME6 function results in the accumulation of fully derepressed levels (70- to 100-fold increase above basal level) of early meiotic transcripts during vegetative growth. In contrast, mutations in five previously identified UME loci (UME1 to UME5), result in low to moderate derepression (2- to 10-fold increase) of early meiotic genes. The behavior of insertion and deletion alleles indicates that UME6 is dispensable for mitotic division but is required for meiosis and spore germination. Despite the high level of meiotic gene expression during vegetative growth, the generation times of ume6 mutant haploid and diploid cells are only slightly reduced. However, both ascus formation and spore viability are affected more severely. The UME6 gene encodes a 91-kD protein that contains a C6 zinc cluster motif similar to the DNA-binding domain of GAL4. The integrity of this domain is required for UME6 function. It has been reported recently that a mutation in CAR80 fails to complement an insertion allele of UME6. CAR80 is a gene required for nitrogen repression of the arginine catabolic enzymes. Here, through sequence analysis, we demonstrate that UME6 and CAR80 are identical. Analyses of UME6 mRNA during both nitrogen starvation and meiotic development indicate that its transcription is constitutive, suggesting that regulation of UME6 activity occurs at a post-transcriptional level.
本报告描述了UME6（CAR80/CARGRI）的鉴定、克隆及分子分析，UME6是减数分裂早期基因表达的关键转录调节因子。UME6功能缺失导致在营养生长期间减数分裂早期转录本积累到完全去抑制水平（比基础水平增加70至100倍）。相比之下，先前鉴定的五个UME位点（UME1至UME5）的突变导致减数分裂早期基因低至中度去抑制（增加2至10倍）。插入和缺失等位基因的行为表明UME6对于有丝分裂是可有可无的，但对于减数分裂和孢子萌发是必需的。尽管在营养生长期间减数分裂基因表达水平很高，但ume6突变体单倍体和二倍体细胞的世代时间仅略有缩短。然而，子囊形成和孢子活力受到的影响更为严重。UME6基因编码一种91-kD蛋白，该蛋白含有一个与GAL4的DNA结合结构域相似的C6锌簇基序。该结构域的完整性是UME6功能所必需的。最近有报道称，CAR80中的一个突变不能互补UME6的插入等位基因。CAR80是精氨酸分解代谢酶氮抑制所必需的基因。在这里，通过序列分析，我们证明UME6和CAR80是相同的。对氮饥饿和减数分裂发育过程中UME6 mRNA的分析表明其转录是组成型的，这表明UME6活性的调节发生在转录后水平。
