Springer Online Journal Archives 1860-2000
Abstract InArabidopsis thaliana, catalase is encoded by a small gene family. We have characterized cDNA and genomic clones containing theArabidopsis catalase geneCAT3, present as a single copy in the nuclear genome. Six introns were identified in theCAT3 coding region and two transcription start sites have been been mapped by primer extension. The deduced amino acid sequence of CAT3 is highly similar to other catalases.CAT3 expression is similar in seedlings germinated and grown either in continuous light or in continuous dark, suggesting thatCAT3 expression in seedlings is not light responsive.CAT3 expression is controlled by the circadian clock; in 5-week-old plants grown on a light-dark cycle and then transferred to continuous light, robust oscillations inCAT3 mRNA abundance with circadian period persist for at least five circadian cycles. Interestingly, the peak inCAT3 mRNA abundance occurs in the subjective evening, which is out of phase with expression of theArabidopsis CAT2 catalase gene, which shows clock-regulated expression gated to the subjective early morning.
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