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ARS Home » Midwest Area » Urbana, Illinois » Global Change and Photosynthesis Research » Research » Publications at this Location » Publication #197848
Title: ISOFORM-SPECIFIC BINDING OF 14-3-3 PROTEINS TO NITRATE REDUCTASE AND THE BRASSINOSTEROID INSENSITIVE 1 RECEPTOR KINASE SIGNALING COMPLEX

Author
item Oh, Man Ho
item HUBER, JOAN - UNIVERSITY OF ILLINOIS
item WANG, XIAOFENG - NC STATE UNIVERSITY
item FERL, ROBERT - UNIVERSITY OF FLORIDA
item CLOUSE, STEVEN - NC STATE UNIVERSITY
item Huber, Steven

Submitted to: American Society of Plant Biologists
Publication Type: Abstract Only
Publication Acceptance Date: 3/1/2006
Publication Date: 7/1/2006
Citation: Oh, M., Huber, J.L., Wang, X., Ferl, R., Clouse, S.D., Huber, S.C. 2006. Isoform-specific binding of 14-3-3 proteins to nitrate reductase and the brassinosteroid insensitive 1 receptor kinase signaling complex [abstract]. American Society of Plant Biologists [abstract]. Paper no. 36033. Available: http://abstracts.aspb.org/pb2006/public/P36/P36033.html,

Interpretive Summary:

Technical Abstract: The 14-3-3 proteins are known to bind many different soluble protein clients, but less is known about binding to integral membrane proteins, and in both cases the issue of isoform specificity remains largely unexplored. Using an array of anti-14-3-3 antibodies and 2-dimensional electrophoresis (2-DE), we are resolving and identifying 14-3-3 isoforms present in Arabidopsis leaves. Charge trains on 2-DE and cross reactivity with anti-phosphothreonine antibodies, suggests that 14-3-3s are phosphorylated on threonine residue(s) in vivo. However, the sites and function remain unclear. 14-3-3s immunoprecipitate (IP) with nitrate reductase (NR), as expected, and also with the leucine-rich repeat, receptor-like kinase, BRI1. 14-3-3s binds to BRI1 in a ligand (brassinolide)-stimulated manner, concurrent with BRI1 autophosphorylation. With both NR and BRI1, one common mode of action of 14-3-3 binding appears to be to decrease the proteolytic degradation of the client protein. In the case of NR, over expression of a directed mutant of 14-3-3 omega (E208A), which has increased affinity for phospho-NR, results in increased NR phosphorylation at the Ser-534 site, increased NR protein level, and increased NR protein stability (~3-fold increase in half-life). In the case of BRI1, presence of ligand results in increased BRI1 protein level (~ 2.5-fold), concurrent with increased 14-3-3 binding. Thus, for NR and BRI1, 14-3-3 binding may reduce client degradation. The cellular content of 14-3-3 proteins may also be regulated, as size-exclusion chromatography of soluble Arabidopsis leaf proteins suggests that the majority of 14-3-3s contain a bound client. Currently, we are identifying which protein(s) in the BRI1-signaling complex are binding 14-3-3 proteins.