Oliveira Edna M M, Martins Adriana S, Carvajal Elvira, Bon Elba P S
Instituto de Química, UFRJ, Rio de Janeiro, RJ, Brasil.
Yeast. 2003 Jan 15;20(1):31-7. doi: 10.1002/yea.930.
The role of Gln3p, Nil1p, Dal80p and Ure2p in the nitrogen regulation of ASP3, which codes for the periplasmic Saccharomyces cerevisiae asparaginase II, was investigated. Analysis of enzyme levels and mRNA(ASP3) in two wild-type strains and gln3, nil1, gln3nil1, gln3ure2, nil1ure2, nil1dal80, ure2, dal80 and ure2dal80 mutant cells allowed the study of the qualitative and quantitative regulatory role of the GATA factors and Ure2p on ASP3 expression. The simultaneous presence of Gln3p and Nil1p is a required condition for full gene transcription. Enzyme activity doubled upon nitrogen starvation of either ammonium-grown (possibly due to Nil2p/Deh1p derepression) or proline-grown (due to Dal80p derepression) cells. The ure2 mutation increased enzyme levels five-fold in fresh ammonium-grown cells and ten-fold in fresh proline-grown cells. The combined effects of the ure2 mutation and nitrogen starvation on ammonium- or proline-grown cells resulted in an overall 10-20-fold enzyme activity increase, respectively, in comparison with the wild-type cells.
研究了Gln3p、Nil1p、Dal80p和Ure2p在编码酿酒酵母周质天冬酰胺酶II的ASP3的氮调节中的作用。通过分析两种野生型菌株以及gln3、nil1、gln3nil1、gln3ure2、nil1ure2、nil1dal80、ure2、dal80和ure2dal80突变细胞中的酶水平和mRNA（ASP3），研究了GATA因子和Ure2p对ASP3表达的定性和定量调节作用。Gln3p和Nil1p同时存在是基因完全转录的必要条件。在以铵生长（可能由于Nil2p/Deh1p去阻遏）或以脯氨酸生长（由于Dal80p去阻遏）的细胞氮饥饿时，酶活性增加一倍。ure2突变使新鲜铵生长细胞中的酶水平增加5倍，在新鲜脯氨酸生长细胞中增加10倍。与野生型细胞相比，ure2突变和氮饥饿对铵或脯氨酸生长细胞的联合作用分别导致酶活性总体增加10至20倍。
