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Precursor processing for plant peptide hormone maturation by subtilisin-like serine proteinases

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Science  23 Dec 2016:
Vol. 354, Issue 6319, pp. 1594-1597
DOI: 10.1126/science.aai8550

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Prohormone processing by subtilases

A flower that has gone to seed will drop its petals in a regulated process called abscission. Schardon et al. analyzed the production of the peptide hormone that regulates floral organ abscission in the model plant Arabidopsis thaliana. They used tissue-specific expression of proteinase inhibitors to identify the subtilisin-like proteinases that act as prohormone convertases required for peptide hormone production in plants.

Science, this issue p. 1594

Abstract

Peptide hormones that regulate plant growth and development are derived from larger precursor proteins by proteolytic processing. Our study addressed the role of subtilisin-like proteinases (SBTs) in this process. Using tissue-specific expression of proteinase inhibitors as a tool to overcome functional redundancy, we found that SBT activity was required for the maturation of IDA (INFLORESCENCE DEFICIENT IN ABSCISSION), a peptide signal for the abscission of floral organs in Arabidopsis. We identified three SBTs that process the IDA precursor in vitro, and this processing was shown to be required for the formation of mIDA (the mature and bioactive form of IDA) as the endogenous signaling peptide in vivo. Hence, SBTs act as prohormone convertases in plants, and several functionally redundant SBTs contribute to signal biogenesis.

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