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The stability of the Chlorella nitrate reductase mRNA is determined by the secondary structure of the 5′-UTR: implications for posttranscriptional regulation of nitrate reductase

Cannons, Andrew C., Cannon, Jennifer
Planta 2002 v.214 no.3 pp. 488-491
Chlorella vulgaris, genes, messenger RNA, nitrate reductase, nitrogen, nucleotides, transcription (genetics)
Nitrate reductase (NR; EC can be controlled at both transcriptional and posttranscriptional levels. Here we describe stability of NR mRNA as a mechanism of control. The NR gene in Chlorella vulgaris (Warburg strain) transcribes a stable mRNA and an unstable mRNA. In-vitro-synthesized transcripts representing these mRNAs show the same stability characteristics. The unstable mRNA is 30 nucleotides longer at the 5′-UTR compared to the stable mRNA. Using an RNA-folding program the 5′-UTR of the longer unstable RNA showed a more extensive stem-loop structure compared to the more linear form of the shorter stable mRNA. Transcripts representing RNAs with intermediate 5′-UTRs folded similarly to the long form and were unstable, or similarly to the short form and were more stable. Thus the secondary structure of the 5′-UTR of NR mRNA is important in the stability of NR transcripts in Chlorella and allows the cell to respond to changes in nitrogen source in an energy-efficient manner.