membrane-associated thioredoxin required for plant growth moves from cell to cell, suggestive of a role in intercellular communication

Thioredoxins (Trxs) are small ubiquitous regulatory disulfide proteins. Plants have an unusually complex complement of Trxs composed of six well-defined types (Trxs f, m, x, y, h, and o) that reside in different cell compartments and function in an array of processes. The extraplastidic h type consi...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 2010-02, Vol.107 (8), p.3900-3905
Main Authors: Meng, Ling, Wong, Joshua H, Feldman, Lewis J, Lemaux, Peggy G, Buchanan, Bob B
Format: Article
Language:English
Subjects:
Amino Acid Sequence
Animal cells
Antioxidants
Arabidopsis - genetics
Arabidopsis - growth & development
Arabidopsis Proteins - chemistry
Arabidopsis Proteins - genetics
Arabidopsis Proteins - physiology
Arabidopsis thaliana
Biological Sciences
Cell Communication
Cell Membrane - metabolism
Cell membranes
Cell motility
Cell walls
Cells
Cysteine - genetics
cytochemistry
Epidermal cells
Flowers & plants
Glycine - genetics
intercellular communication
Mutagenesis
mutants
Mutation
Onions
Plant biology
Plant cells
Plant growth
plant proteins
Plants
plasma membrane
Plastids - metabolism
Protein Conformation
Proteins
Thioredoxin
Thioredoxins - chemistry
Thioredoxins - genetics
Thioredoxins - physiology
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Summary:Thioredoxins (Trxs) are small ubiquitous regulatory disulfide proteins. Plants have an unusually complex complement of Trxs composed of six well-defined types (Trxs f, m, x, y, h, and o) that reside in different cell compartments and function in an array of processes. The extraplastidic h type consists of multiple members that in general have resisted isolation of a specific phenotype. In analyzing mutant lines in Arabidopsis thaliana, we identified a phenotype of dwarf plants with short roots and small yellowish leaves for AtTrx h9 (henceforth, Trx h9), a member of the Arabidopsis Trx h family. Trx h9 was found to be associated with the plasma membrane and to move from cell to cell. Controls conducted in conjunction with the localization of Trx h9 uncovered another h-type Trx in mitochondria (Trx h2) and a Trx in plastids earlier described as a cytosolic form in tomato. Analysis of Trx h9 revealed a 17-amino acid N-terminal extension in which the second Gly (Gly²) and fourth cysteine (Cys⁴) were highly conserved. Mutagenesis experiments demonstrated that Gly² was required for membrane binding, possibly via myristoylation. Both Gly² and Cys⁴ were needed for movement, the latter seemingly for protein structure and palmitoylation. A three-dimensional model was consistent with these predictions as well as with earlier evidence showing that a poplar ortholog is reduced by a glutaredoxin rather than NADP-thioredoxin reductase. In demonstrating the membrane location and intercellular mobility of Trx h9, the present results extend the known boundaries of Trx and suggest a role in cell-to-cell communication.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.0913759107