In Chlamydomonas reinhardtii, the expression of the Nia1 gene encoding NAD(P)H nitrate reductase is controlled at the transcriptional level, positively by light and negatively by ammonium. Previous work has shown that the region −279 to +269 with respect to the start site of transcription was sufficient to confer regulated expression of a promoterless arylsulfatase (Ars) reporter gene. To understand the mechanisms underlying this regulation, the −279 to +2 sequence was analysed for the presence of ammonium-responsive elements using either pJD54 (promoterless Ars gene) or pJD100 (minimal β-tubulin promoter-driven Ars gene). The region lying between −195 and −120 was shown to be dispensable. Essential responsive elements were found in four distinct regions between −231 and −219, −120 and −100, −76 and −65 and −33 and −8. Each of these sequences is required for maximal expression in the absence of ammonium and a conserved GGA/TAGGGT motif is present in two of these regions. Several deletions within the region −33 to −77 were shown to partially relieve the transformants from the negative effect of ammonium. These experiments demonstrate that Nia1 expression is promoted by at least four elements between −231 and −8 and suggest that part of the repression by ammonium takes place through a proximal element located in the −51 to − 33 sequence.
Plant Molecular Biology – Springer Journals
Published: Oct 4, 2004
It’s your single place to instantly
discover and read the research
that matters to you.
Enjoy affordable access to
over 18 million articles from more than
15,000 peer-reviewed journals.
All for just $49/month
Query the DeepDyve database, plus search all of PubMed and Google Scholar seamlessly
Save any article or search result from DeepDyve, PubMed, and Google Scholar... all in one place.
All the latest content is available, no embargo periods.
“Whoa! It’s like Spotify but for academic articles.”@Phil_Robichaud