Journal Article

Effects of PII Deficiency on Expression of the Genes Involved in Ammonium Utilization in the Cyanobacterium <i>Synechocystis</i> sp. Strain PCC 6803

Nobuyuki Takatani and Tatsuo Omata

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 47, issue 6, pages 679-688
Published in print June 2006 | ISSN: 0032-0781
Published online June 2006 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pcj037
Effects of PII Deficiency on Expression of the Genes Involved in Ammonium Utilization in the Cyanobacterium Synechocystis sp. Strain PCC 6803

More Like This

Show all results sharing these subjects:

  • Biochemistry
  • Molecular and Cell Biology
  • Plant Sciences and Forestry

GO

Show Summary Details

Preview

The Synechocystis sp. strain PCC 6803 mutant deficient in PII protein (the glnB gene product) was found to express glutamine synthetase activity at levels several times higher than the wild-type strain. There was no significant difference in nitrate reductase activity levels between the two strains, and the nitrite reductase levels were somewhat lower in the mutant than in the wild-type strain. The higher glutamine synthetase activity in the mutant was ascribed to higher expression levels of the glutamine synthetase genes (glnA and glnN), which belong to the regulon controlled by NtcA, a Crp-family transcription regulator. Examination of the effects of PII deficiency on other NtcA-regulated genes revealed that the transcript levels of amt1 (encoding an ammonium permease) and gifB (encoding an inhibitor of glutamine synthetase) were increased, whereas that of gifA (a homolog of gifB, encoding another glutamine synthetase inhibitor) was decreased, with those of nirA, nrtC, icd, sigE (rpoD2-V), nblA and ntcA being unaffected. Unlike the Synechococcus elongatus strain PCC 7942, induction or repression of the NtcA-regulated genes proceeded normally in the PII-deficient mutant upon nitrogen depletion. The altered steady-state expression levels of glnA, glnN, amt1, gifA and gifB in the PII-deficient mutant suggested that Synechocystis sp. strain PCC 6803 has a mechanism for regulation of the subset of the NtcA-regulated genes related directly to ammonium assimilation.

Keywords: Ammonium assimilation; Cyanobacterium; Gene regulation; Glutamine synthetase; PII protein; Synechocystis sp. strain PCC 6803; GS, glutamine synthetase; NAGK, N-acetyl-l-glutamate kinase; NiR, nitrite reductase; NR, nitrate reductase; NRT, nitrate/nitrite transporter; 2-OG, 2-oxoglutarate

Journal Article.  6559 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

Full text: subscription required

How to subscribe Recommend to my Librarian

Users without a subscription are not able to see the full content. Please, subscribe or login to access all content.