ISSN:
1365-2958
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
,
Medicine
Notes:
Nitrogen metabolism is a highly regulated process in Neurospora crassa. The structural genes that encode nitrogen catabolic enzymes are subject to nitrogen metabolite repression, mediated by the positive-acting NIT2 protein and by the negative-acting NMR protein. NIT2, a globally acting factor, is a member of the GATA family of regulatory proteins and has a single Cys2/Cys2 zinc finger DNA-binding domain. The negative-acting NMR protein interacts via specific protein–protein binding with two distinct regions of the NIT2 protein, a short alpha-helical motif within the NIT2 DNA-binding domain and a second motif at its carboxy terminus. Deletions of segments of NIT2 throughout most of its length result in truncated proteins, which are still functional for activating gene expression; most of these mutant NIT2 proteins still allow proper nitrogen repression of nitrate reductase synthesis. In contrast, deletions or certain amino acid substitutions within the zinc finger and the carboxy-terminal tail result in a loss of nitrogen metabolite repression. Those mutated forms of NIT2 that are insensitive to nitrogen repression have also lost one of the NIT2–NMR protein–protein interactions. These results provide compelling evidence that the specific NIT2–NMR interactions have a regulatory function and play a central role in establishing nitrogen metabolite repression.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1046/j.1365-2958.1997.6041979.x
