Haas H, Bauer B, Redl B, Stöffler G, Marzluf G A
Department of Biochemistry, Ohio State University, Columbus 43210, USA.
Curr Genet. 1995 Jan;27(2):150-8. doi: 10.1007/BF00313429.
We have isolated the Penicillium chrysogenum nre gene which is homologous to the major nitrogen regulatory genes areA from Aspergillus nidulans and nit-2 from Neurospora crassa. Overall, nre shows 60% identity to areA and 30% identity to nit-2 at the amino-acid level. The gene encodes a protein of 835 amino-acid residues and contains a single Cys2/Cys2-type zinc finger with an adjacent basic region and a putative acidic activation region. In the DNA-binding domain, 98% of the amino-acid residues are identical in nre, areA and nit-2. The nre gene has been shown to be functional in N. crassa by heterologous complementation of a nit-2 mutant. Growth tests indicated that transformants could utilize nitrate, amino-acids, purines and amides as sole nitrogen sources. Nitrate reductase activity assays performed with transformants demonstrated that nitrogen control was completely normal. Complementation of N. crassa nit-2 mutants with 5'-deletion clones of nre suggests the possible presence of an internal promoter within the coding region. Northern analysis and ribonuclease protection assays of total cellular RNA indicated that nre encodes a 3.2-kb transcript which is reduced in content under conditions of nitrogen repression.
我们已经分离出产黄青霉nre基因，该基因与构巢曲霉的主要氮调节基因areA以及粗糙脉孢菌的nit-2基因同源。总体而言，nre在氨基酸水平上与areA有60%的同一性，与nit-2有30%的同一性。该基因编码一个由835个氨基酸残基组成的蛋白质，包含一个带有相邻碱性区域和一个推定酸性激活区域的单一Cys2/Cys2型锌指。在DNA结合结构域中，nre、areA和nit-2的氨基酸残基98%相同。通过对nit-2突变体的异源互补，已证明nre基因在粗糙脉孢菌中具有功能。生长测试表明，转化体可以利用硝酸盐、氨基酸、嘌呤和酰胺作为唯一氮源。对转化体进行的硝酸还原酶活性测定表明，氮控制完全正常。用nre的5'-缺失克隆对粗糙脉孢菌nit-2突变体进行互补表明，编码区内可能存在一个内部启动子。对总细胞RNA的Northern分析和核糖核酸酶保护测定表明，nre编码一个3.2-kb的转录本，其含量在氮阻遏条件下会降低。
