Shen WC, Ebbole DJ
Department of Plant Pathology and Microbiology, Texas A&M University, College Station, Texas, 77843
Fungal Genet Biol. 1997 Feb;21(1):40-9.
The gene encoding the small subunit of the arginine-specific carbamoyl phosphate synthetase, ARG2, of Magnaporthe grisea was characterized to examine the basic regulation of biosynthetic genes in this plant pathogen. The transcript of the ARG2 gene contains an upstream open reading frame (uORF) that is similar to uORFs found in the homologous genes of Neurospora crassa (arg-2) and Saccharomyces cerevisiae (CPA1), suggesting that the M. grisea gene is translationally regulated by a mechanism that is conserved in these fungi. Amino acid imbalance leads to elevated levels of ARG2 mRNA, indicating that in addition to translational control, ARG2 is subject to cross-pathway transcriptional control. A DNA-binding activity that has properties similar to those of the global transcriptional regulator mediating cross-pathway control in N. crassa was detected in M. grisea cell extracts. Thus, it appears that both specific regulation of ARG2 by arginine and global regulation of amino acid biosynthesis are present in M. grisea and highly conserved among M. grisea, N. crassa, and S. cerevisiae.
为研究这种植物病原体中生物合成基因的基本调控机制，对稻瘟病菌精氨酸特异性氨甲酰磷酸合成酶小亚基的编码基因ARG2进行了特性分析。ARG2基因的转录本包含一个上游开放阅读框（uORF），该uORF与粗糙脉孢菌（arg - 2）和酿酒酵母（CPA1）同源基因中发现的uORF相似，这表明稻瘟病菌基因通过一种在这些真菌中保守的机制进行翻译调控。氨基酸失衡会导致ARG2 mRNA水平升高，这表明除了翻译控制外，ARG2还受到交叉途径转录控制。在稻瘟病菌细胞提取物中检测到一种DNA结合活性，其性质与介导粗糙脉孢菌交叉途径控制的全局转录调节因子相似。因此，似乎精氨酸对ARG2的特异性调控以及氨基酸生物合成的全局调控在稻瘟病菌中均存在，并且在稻瘟病菌、粗糙脉孢菌和酿酒酵母中高度保守。
