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Methylammonium (ammonium) uptake in a glutamine auxotroph of the cyanobacterium Anabaena cycadeae
Author(s) -
Singh D.T.,
Rai A.N.,
Singh H.N.
Publication year - 1985
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(85)81337-5
Subject(s) - glutamine , glutamine synthetase , auxotrophy , ammonium , biochemistry , biology , chemistry , amino acid , escherichia coli , gene , organic chemistry
Methylammonium uptake was studied in a glutamine auxotroph of the cyanobacterium Anabaena cycadeae lacking glutamine synthetase activity. The uptake pattern was found to be biphasic, consisting of an initial fast phase lasting up to 60 s followed by a slower second phase. When cells were preincubated with L‐meth‐ionine‐DL‐sulphoximine, an irreversible inhibitor of glutamine synthetase activity, the second uptake phase was abolished although the first phase was unaffected. Since the glutamine auxotroph did not have any glutamine synthetase activity the inhibition of the second phase by L‐methionine‐DL‐sulphoximine could not have been due to the inhibition of glutamine synthetase activity. Thus, it is suggested that the two uptake phases may represent two different ammonium transport systems, the second one being sensitive to L‐meth‐ionine‐DL‐sulphoximine.