Protein Phosphatase 2A Controls Seedling Growth Through Differential Regulation of Ethylene Biosynthesis

Skottke, Kyle Raymond

Full Metadata

Overview

Year:: 2012
Contributor:: Skottke, Kyle Raymond (creator); DeLong, Alison (Director); Laney, Jeffrey (Reader); Johnson, Mark (Reader); Arthur, Salomon (Reader); Schaller, Eric (Reader); Brown University. BIOMED: Molecular Biology, Cell Biology, and Biochemistry (sponsor)
Genre:: theses
Subject:: PP2A; Ethylene; Plant hormones
Extent:: xiii, 257 p.
DOI: https://doi.org/10.7301/Z0CV4G1V

Files

Description

Abstract:: The gaseous hormone ethylene is a master regulator of development and physiology throughout the plant life cycle. Ethylene biosynthesis is stringently regulated to maintain low basal levels of ethylene production during most phases of vegetative growth but allow for rapid peaks of high production at developmental transitions and under stress conditions. In most tissues ethylene inhibits cell expansion, thus low basal levels of ethylene biosynthesis in dark-grown seedlings are critical for optimal cell expansion during early seedling development. The committed steps in ethylene biosynthesis are performed by the enzymes 1-aminocyclopropane 1-carboxylate synthase (ACS) and 1-aminocyclopropane 1-carboxylate oxidase (ACO). In most tissue types, ACS catalyzes the rate-limiting step in ethylene biosynthesis. The abundance of different ACS enzymes is tightly regulated both by transcriptional control and by post-translational modifications and proteasome-mediated degradation. Here I show that specific ACS isozymes are targets for regulation by protein phosphatase 2A (PP2A) during Arabidopsis thaliana seedling growth, and that reduced PP2A function causes increased ACS activity in the roots curl in 1-N-naphthylphthalamic acid 1 (rcn1) mutant. Genetic analysis reveals that ethylene overproduction in PP2A-deficient plants requires ACS2 and ACS6, genes that encode ACS proteins known to be stabilized by phosphorylation. The stability of the ACS6 protein is increased when PP2A activity is reduced and PP2A and ACS6 proteins associate in seedlings. Additionally, PP2A complexes specifically dephosphorylate a C-terminal ACS6 phosphopeptide. These results suggest that PP2A-dependent destabilization requires RCN1-dependent dephosphorylation of the ACS6 C-terminus. Surprisingly, rcn1 plants exhibit decreased accumulation of the ACS5 protein, suggesting that a regulatory phosphorylation event leads to ACS5 destabilization. These data provide new insight into the circuitry that ensures dynamic control of ethylene synthesis during plant development, showing that PP2A mediates the finely tuned regulation of overall ethylene production by differentially affecting the stability of specific classes of ACS enzymes.
Notes:: Thesis (Ph.D. -- Brown University (2012)

Content

Access Conditions

Rights: In Copyright
Restrictions on Use: Collection is open for research.

Citation

Skottke, Kyle Raymond, "Protein Phosphatase 2A Controls Seedling Growth Through Differential Regulation of Ethylene Biosynthesis" (2012). Molecular Biology, Cell Biology, and Biochemistry Theses and Dissertations. Brown Digital Repository. Brown University Library. https://doi.org/10.7301/Z0CV4G1V

Relations

Collection:

Molecular Biology, Cell Biology, and Biochemistry Theses and Dissertations

Theses and Dissertations for the Molecular Biology, Cell Biology, and Biochemistry department.
...