Open AccessRegulation of nitrate reduction in a cyanobacterium Phormidium uncinatum : Distinctive modes of ammonium‐repression of nitrate and nitrite reductases
Author(s) -
Palod A.,
Chauhan V.S.,
Bagchi S.N.
Publication year - 1990
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.1990.tb13952.x
Subject(s) - nitrate , glutamine synthetase , nitrite , ammonium , psychological repression , ammonia , biochemistry , nitrogen assimilation , nitrite reductase , biology , glutamine , metabolism , enzyme , glutamate synthase , nitrate reductase , chemistry , amino acid , ecology , organic chemistry , gene expression , gene
1. Summary Ammonium regulation of cellular nitrate and nitrite reductases (NR;NiR) was studied in Phormidium uncinatum . Diminished to low activities were found with ammonia and development of the enzymes in its absence required de novo protein synthesis but not nitrate. While an inhibition of ammonium metabolism via glutamine synthetase (GS) activity reversed the ammonium effect on NR. NiR was non‐responsive. Development of NiR in such cultures in absence of ammonia however needed new protein synthesis. These data suggest that ammonia by itself and through assimilation exerts repression control on NiR and NR respectively, which are otherwise derepressed.