Transcriptional regulation of the Nia1 gene encoding nitrate reductase in Chlamydomonas reinhardtii: effects of various environmental factors on the expression of a reporter gene under the control of the Nia1 promoter.

摘要: The NAD(P)H nitrate reductase (NR) from Chlamydomonas reinhardtii is encoded by the structural gene Nia1. Numerous data literature indicate that this enzyme submitted to complex regulation mechanisms involving multiple controls at transcriptional and post-transcriptional levels. To specifically investigate of Nia1 level, NR+ NR- transformed cells harbouring Nia1:Ars construct (Nia1 promoter fused arylsulfatase (ARS)-encoding Ars reporter gene) were cultivated under various experimental conditions ARS activities recorded. levels very low in grown presence NH4Cl dramatically increased on agar medium deprived any nitrogen source or containing nitrate, nitrite, urea, arginine glutamine. Compared nitrogen-free medium, a slight positive effect strain significant negative nitrite both strains observed. high light dark DCMU, indicating transcription strikingly dependent photosynthetic activity. Acetate used as carbon did not substitute for stimulating expression. Inactivation NR tungstate treatment resulted dramatic increase level suggesting Chlamydomonas, like higher plants, active negatively regulates gene. Deleting major part leader sequence still present chimeric decrease but modify pattern.