Interrelated regulation of sulphur-containing amino-acid biosynthetic enzymes and folate-metabolizing enzymes in Aspergillus nidulans.
Interrelated regulation of sulphur-containing amino-acid biosynthetic enzymes and folate-metabolizing enzymes in Aspergillus nidulans.
复制标题
构巢曲霉中含硫氨基酸生物合成酶和叶酸代谢酶的相互关联调节。
DOI：
10.1111/j.1432-1033.1989.tb14716.x
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发表时间：
1989
期刊：
影响因子：
--
通讯作者：
A. Paszewski
中科院分区：
文献类型：
--
作者：
J. Nadolska;M. Balińska;A. Paszewski
在构巢曲霉中，同型半胱氨酸可以代谢为半胱氨酸和蛋氨酸。半胱氨酸合成的主要途径或硫酸盐同化途径受损的突变体表现出谷胱甘肽含量低，同型半胱氨酸合酶和同型半胱氨酸至半胱氨酸途径酶的水平升高。另一方面，这些突变体中蛋氨酸合酶和其他叶酸代谢酶的水平降低。这种反协调调节提供了一种控制同型半胱氨酸在两条不同途径之间分配的机制。研究发现，在携带抑制metA、metB和metG基因突变的突变菌株中，同型半胱氨酸合酶和叶酸酶均被去抑制。这些结果表明同型半胱氨酸合酶可被视为甲硫氨酸合成的替代途径的酶，并强烈表明控制含硫氨基酸和叶酸代谢的调节机制是相互关联的。
In Aspergillus nidulans homocysteine can be metabolized both to cysteine and methionine. Mutants impaired in the main pathway of cysteine synthesis or in the sulphate assimilation pathway show a low pool of glutathione and elevated levels of homocysteine synthase and of the homocysteine-to-cysteine pathway enzymes. On the other hand, the level of methionine synthase and other enzymes of folate metabolism is depressed in these mutants. This anticoordinated regulation provides a mechanism controlling the partition of homocysteine between the two diverging pathways. Homocysteine synthase was found derepressed, along with folate enzymes, in a strain carrying a mutation which suppresses mutations in metA, metB and metG genes. These results indicate that homocysteine synthase can be regarded as the enzyme of an alternative pathway of methionine synthesis and strongly suggest that the regulatory mechanisms governing sulphur-containing amino acid and folate metabolisms are interrelated.