Premium
Independence of carbon and nitrogen control in the posttranslational regulation of nitrate transport in the cyanobacterium Synechococcus sp. strain PCC 7942
Author(s) -
Rodrı́guez Rocı́o,
Kobayashi Masaki,
Omata Tatsuo,
Lara Catalina
Publication year - 1998
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/s0014-5793(98)00865-5
Subject(s) - nitrate , ammonium , biochemistry , mutant , carbon fixation , chemistry , nitrogen assimilation , nitrogen fixation , nitrogen , biology , photosynthesis , gene , organic chemistry
Nitrate transport by Synechococcus sp. strain PCC 7942 cells was inhibited by ammonium and by inhibitors of CO 2 fixation. Ammonium assimilation inhibitors, such as l ‐methionine d,l ‐sulfoximine, were known to prevent the negative effects of ammonium and of inhibitors of CO 2 fixation on nitrate uptake, leading to propose that CO 2 fixation was required to counteract the feed‐back inhibition of nitrate assimilation. In NR‐less mutants, l ‐methionine d,l ‐sulfoximine prevented the negative effects of ammonium on nitrate transport, but not always prevented those of inhibiting CO 2 fixation. The carboxy‐terminal domain of the NrtC subunit of the nitrate transporter has recently been identified as a regulatory domain involved in N‐control. The mutant strain NC2, constructed by deleting the 3′ portion of nrtC , showed high nitrate transport activity insensitive to ammonium but sensitive to inhibitors of CO 2 fixation. These findings indicate that the C‐control and the N‐control of nitrate transport are independent at both the physiological and the molecular level.