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Plant Mol Biol. 2000 Nov;44(5):649-57.

Circadian and senescence-enhanced expression of a tobacco cysteine protease gene.

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National Institute of Agrobiological Resources, Tsukuba, Ibaraki, Japan.


A cDNA clone encoding a cysteine protease was isolated from a tobacco cDNA library, utilizing as a probe a PCR fragment obtained from degenerated primers based on the conserved sequences of plant cysteine protease genes. A putative protein encoded by the clone NTCP-23 had an amino acid sequence with significant similarities to those of plant senescence-associated cysteine proteases and mammalian cathepsin H. Northern blot analysis showed that NTCP-23 mRNA is expressed in all organs and the mRNA and protein expression is enhanced during natural senescence. We propose that NTCP-23 is responsible for amino acid remobilization especially in senescencing leaves. Furthermore, it was found that the mRNA expression follows a circadian rhythm and is reduced by continuous darkness, wounding and hypersensitive reaction (HR). NTCP-23 is the first cysteine protease whose mRNA expression has been shown to be temporarily reduced by wounding.

[Indexed for MEDLINE]

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