Induction of sporulation in Saccharomyces cerevisiae leads to the formation of N6-methyladenosine in mRNA:: a potential mechanism for the activity of the IME4 gene
Induction of sporulation in Saccharomyces cerevisiae leads to the formation of N6-methyladenosine in mRNA:: a potential mechanism for the activity of the IME4 gene
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DOI：
10.1093/nar/gkf573
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发表时间：
2002-10-15
影响因子：
14.9
通讯作者：
Bokar, JA
中科院分区：
文献类型：
--
作者：
Clancy, MJ;Shambaugh, ME;Bokar, JA
N - 6 - 甲基腺苷（m(6)A）存在于从所有高等真核生物中分离出的mRNA的内部位点，但此前在酿酒酵母（Saccharomyces cerevisiae）的mRNA中未被检测到。这种核苷修饰仅在特定序列环境下发生，且在不同物种中似乎是保守的。这种修饰的功能尚未完全确定，但有一些间接证据表明m(6)A可能在mRNA剪接、运输或翻译的效率方面发挥作用。酿酒酵母中对孢子形成诱导很重要的IME4基因与人类的MT - A70基因非常相似，MT - A70基因已被证明是人类mRNA [N - 6 - 腺苷] - 甲基转移酶的一个关键亚基。这一观察结果引出一个假设，即酵母的孢子形成可能依赖于由Ime4p介导的酵母mRNA的甲基化。在这项研究中，我们表明孢子形成的诱导导致酵母mRNA中出现低水平的m(6)A，并且这种修饰需要IME4基因。此外，在Ime4p的假定催化残基上进行单氨基酸替换，会导致在一个其孢子形成能力完全依赖于此蛋白的菌株中出现严重的孢子形成缺陷。总体而言，这些数据非常有力地表明，Ime4p对孢子形成的激活是其假定的甲基转移酶活性的结果，并提供了迄今为止关于m(6)A在基因调控途径中的生理作用的最直接证据。
N-6-Methyladenosine (m(6)A) is present at internal sites in mRNA isolated from all higher eukaryotes, but has not previously been detected in the mRNA of the yeast Saccharomyces cerevisiae. This nucleoside modification occurs only in a sequence- specific context that appears to be conserved across diverse species. The function of this modification is not fully established, but there is some indirect evidence that m(6)A may play a role in the efficiency of mRNA splicing, transport or translation. The S.cerevisiae gene IME4, which is important for induction of sporulation, is very similar to the human gene MT-A70, which has been shown to be a critical subunit of the human mRNA [N-6-adenosine]-methyltransferase. This observation led to the hypothesis that yeast sporulation may be dependent upon methylation of yeast mRNA, mediated by Ime4p. In this study we show that induction of sporulation leads to the appearance of low levels of m(6)A in yeast mRNA and that this modification requires IME4. Moreover, single amino acid substitutions in the putative catalytic residues of Ime4p lead to severe sporulation defects in a strain whose sporulation ability is completely dependent on this protein. Collectively, these data suggest very strongly that the activation of sporulation by Ime4p is the result of its proposed methyltransferase activity and provide the most direct evidence to date of a physiologic role of m(6)A in a gene regulatory pathway.