Gametogenesis in the Chlamydomonas reinhardtii minus mating type is controlled by two genes, MID and MTD1
Gametogenesis in the Chlamydomonas reinhardtii minus mating type is controlled by two genes, MID and MTD1
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DOI：
10.1534/genetics.106.066167
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发表时间：
2007-06-01
期刊：
影响因子：
3.3
通讯作者：
Goodenough, Ursula W.
中科院分区：
文献类型：
--
作者：
Lin, Huawen;Goodenough, Ursula W.
在单细胞藻类莱茵衣藻中，正负交配类型由复杂基因座 MT 控制，其中 MT 基因座中的显性 MID 基因已被证明对于响应氮消耗而表达负特异性配子特异性基因是必需的。我们报告了配子发生过程中 MID 表达模式以及 MT 基因座特有的第二个基因 MTD1 的研究。营养细胞表达基础水平的 MID。脱氮后MID转录的早期激活及其与植物的序列相似性。 RWP-RK 蛋白参与氮响应过程，表明中构象/活性可能对氮敏感。 MID 上调的第二阶段与负配子中交配能力的获得相关。在负菌株中，通过 RNAi 对 MTD1 进行 Kuockdown 会导致在缺氮后无法分化为任一交配类型的配子。我们认为中间MID水平足以激活MTD1转录并抑制正配子特异性基因，并且MTD1表达反过来允许开启负配子特异性基因所需的阈值水平MID表达。我们进一步提出，利用 MT+ 基因座中编码的至少一种基因产物的 MTD1 等效系统在正配子发生过程中是可操作的。
In the unicellular algae Chlamydomonas reinhardtii, the plus and minus mating types are controlled by a Complex locus, MT, where the dominant MID gene in the MT- locus has been shown to be necessary for expression of minus-specific gamete-specific genes in response to nitrogen depletion. We report studies on MID expression patterns during gametogencsis and on a second gene unique to the MT- locus, MTD1 Vegetative cells express basal levels of MID. An early activation of MID transcription after nitrogen re-moval, and its sequence similarity to plant. RWP-RK proteins involved in nitrogen-responsive processes, Suggest that Mid conformation/activity may be nitrogen sensitive. A second stage of MID upregulation correlates with the acquisition of mating ability in minus gametes. Kuockdown of MTD1 by RNAi in minus strains results in a failure to differentiate into gametes of either mating type after nitrogen deprivation. We propose that intermediate Mid levels are sufficient to activate MTD1 transcription and to repress plus gamete-specific genes and that MTD1 expression in turn allows the threshold-level MID expression needed to turn on minus gamete-specific genes. We further propose that an MTD1-equivalent system, utilizing at least one gene product encoded in the MT+ locus, is operant during plus gametogenesis.