Proteinase Activity during Tracheary Element Differentiation in Zinnia Mesophyll Cultures

To address the possibility that proteinases extracted from undifferentiated cells present in tracheary element cultures could catalyze the nonspecific proteolysis illustrated by Figure 2, we developed a singlecell assay to visualize proteolysis associated with different cell types

E. P. Beers

2016

Scholarcy highlights

  • The zinnia mesophyll cell culture tracheary element system was used to study proteinases active during developmentally programmed cell death
  • The 28- and 24-kD proteinases were inhibited by thiol proteinase inhibitors, leupeptin, and N-[N-(1-3trans-carboxirane-2-carbonyl)-~-leucyll-agmatine(E-64). l h e 145and 59-kD proteinases were inhibited by the serine proteinase inhibitor phenylmethylsulfonyl fluoride
  • Using mesophyll cells isolated from the young leaves of Zinnia elegans, TE differentiation can be reproduced in culture. with few exceptions, the events of TE differentiation in culture proceed at a similar rate and in the same manner as those in the intact leaf.In culture, isolated cells are initially homogeneous, and differentiation into TEs occurs semisynchronously in 40 to 60% of living cells by 72 h
  • Z. elegans protein for the substrate gels was extracted in the presence of E-64 and PMSF from cells that were cultured in an inductive medium for 72 h as described above
  • To address the possibility that proteinases extracted from undifferentiated cells present in TE cultures could catalyze the nonspecific proteolysis illustrated by Figure 2, we developed a singlecell assay to visualize proteolysis associated with different cell types
  • Regardless of the cell culture experiment or the tissue type we examined, results from the proteinase inhibitor treatments can be summarized as follows: proteinases 36 kD or smaller were inhibited by E-64, and those migrating as 59-kD or larger proteins were inhibited by PMSF.Other Ser proteinase inhibitors, such as 3,4-dichloroisocoumarin and 4-(2-aminoethyl)benzenesulfonyl fluoride hydrochloride, did not inhibit any of the proteinases detected by the activity gels
  • Plant Cell 6: 1427-1439 Ye Z-H, Varner JEGene expression patterns associated with in vitro tracheary element formation in isolated single mesophyll cells of Zinnia elegans

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