Saccharomyces cerevisiae GATA sequences function as TATA elements during nitrogen catabolite repression and when Gln3p is excluded from the nucleus by overproduction of Ure2p
Saccharomyces cerevisiae GATA sequences function as TATA elements during nitrogen catabolite repression and when Gln3p is excluded from the nucleus by overproduction of Ure2p
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DOI：
10.1074/jbc.m001648200
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发表时间：
2000-06-09
影响因子：
4.8
通讯作者：
Cooper, TG
中科院分区：
文献类型：
--
作者：
Cox, KH;Rai, R;Cooper, TG
酿酒酵母选择性地利用好的氮源（谷氨酰胺）而不是差的氮源（脯氨酸），通过抑制加塔因子依赖的基因转录来运输和分解差的氮源，这一生理过程称为氮分解代谢物抑制（NCR）。较短的转录本的合成是NCR敏感的，而较长的转录本的合成则不是。较长的转录物也在gEn 3 Delta突变体中占主导地位，而与所提供的氮源无关。我们证明，较长的mRNA种类出现通过使用替代的Gln 3 p-结合位点（GATAAs）能够作为替代TATA元件所产生的转录起始位点。GATAA作为替代TATA的能力，即当较短的NCR敏感性转录物的合成被抑制时，与增强的绿色荧光蛋白（EGFP）-Gln 3 p在细胞质中的螯合相关，其方式与EGFP-Ure 2 p所见的方式不可区分。然而，当较短的NCR敏感性DAL 5转录物占优势时，EGFP-Gln 3 p是核的。这些数据表明NCR的潜在机制涉及Ure 2 p与Gln 3 p的细胞质缔合，这是一种阻止Gln 3 p到达NCR敏感基因上游结合位点的相互作用。
Saccharomyces cerevisiae selectively uses good nitrogen sources (glutamine) in preference to poor ones (proline) by repressing GATA factor-dependent transcription of the genes needed to transport and catabolize poor nitrogen sources, a physiological process designated nitrogen catabolite repression (NCR), We show that some NCR-sensitive genes (CAN1, DAL5, DUR1,2, and DUR3) produce two transcripts of slightly different sizes. Synthesis of the shorter transcript is NCR-sensitive and that of the longer transcript is not. The longer transcript also predominates in gEn3 Delta mutants irrespective of the nitrogen source provided. We demonstrate that the longer mRNA species arises through the use of an alternative transcription start site generated by Gln3p-binding sites (GATAAs) being able to act as surrogate TATA elements. The ability of GATAAs to serve as surrogate TATAs, i.e, when synthesis of the shorter, NCR-sensitive transcripts are inhibited, correlates with sequestration of enhanced green fluorescent protein (EGFP)-Gln3p in the cytoplasm in a way that is indistinguishable from that seen with EGFP-Ure2p, However, when the shorter, NCR-sensitive DAL5 transcript predominates, EGFP-Gln3p is nuclear. These data suggest that the mechanism underlying NCR involves the cytoplasmic association of Ure2p with Gln3p, an interaction that prevents Gln3p from reaching it is binding sites upstream of NCR-sensitive genes.