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GFP Tagging of Sieve Element Occlusion (SEO) Proteins Results in Green Fluorescent Forisomes

Forisomes are Ca(2+)-driven, ATP-independent contractile protein bodies that reversibly occlude sieve elements in faboid legumes. They apparently consist of at least three proteins; potential candidates have been described previously as ‘FOR’ proteins. We isolated three genes from Medicago truncatul...

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Autores principales: Pélissier, Hélène C., Peters, Winfried S., Collier, Ray, van Bel, Aart J. E., Knoblauch, Michael
Formato: Texto
Lenguaje:English
Publicado: Oxford University Press 2008
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2582178/
https://www.ncbi.nlm.nih.gov/pubmed/18784195
http://dx.doi.org/10.1093/pcp/pcn141
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author Pélissier, Hélène C.
Peters, Winfried S.
Collier, Ray
van Bel, Aart J. E.
Knoblauch, Michael
author_facet Pélissier, Hélène C.
Peters, Winfried S.
Collier, Ray
van Bel, Aart J. E.
Knoblauch, Michael
author_sort Pélissier, Hélène C.
collection PubMed
description Forisomes are Ca(2+)-driven, ATP-independent contractile protein bodies that reversibly occlude sieve elements in faboid legumes. They apparently consist of at least three proteins; potential candidates have been described previously as ‘FOR’ proteins. We isolated three genes from Medicago truncatula that correspond to the putative forisome proteins and expressed their green fluorescent protein (GFP) fusion products in Vicia faba and Glycine max using the composite plant methodology. In both species, expression of any of the constructs resulted in homogenously fluorescent forisomes that formed sieve tube plugs upon stimulation; no GFP fluorescence occurred elsewhere. Isolated fluorescent forisomes reacted to Ca(2+) and chelators by contraction and expansion, respectively, and did not lose fluorescence in the process. Wild-type forisomes showed no affinity for free GFP in vitro. The three proteins shared numerous conserved motifs between themselves and with hypothetical proteins derived from the genomes of M. truncatula, Vitis vinifera and Arabidopsis thaliana. However, they showed neither significant similarities to proteins of known function nor canonical metal-binding motifs. We conclude that ‘FOR’-like proteins are components of forisomes that are encoded by a well-defined gene family with relatives in taxa that lack forisomes. Since the mnemonic FOR is already registered and in use for unrelated genes, we suggest the acronym SEO (sieve element occlusion) for this family. The absence of binding sites for divalent cations suggests that the Ca(2+) binding responsible for forisome contraction is achieved either by as yet unidentified additional proteins, or by SEO proteins through a novel, uncharacterized mechanism.
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spelling pubmed-25821782009-02-25 GFP Tagging of Sieve Element Occlusion (SEO) Proteins Results in Green Fluorescent Forisomes Pélissier, Hélène C. Peters, Winfried S. Collier, Ray van Bel, Aart J. E. Knoblauch, Michael Plant Cell Physiol Regular Papers Forisomes are Ca(2+)-driven, ATP-independent contractile protein bodies that reversibly occlude sieve elements in faboid legumes. They apparently consist of at least three proteins; potential candidates have been described previously as ‘FOR’ proteins. We isolated three genes from Medicago truncatula that correspond to the putative forisome proteins and expressed their green fluorescent protein (GFP) fusion products in Vicia faba and Glycine max using the composite plant methodology. In both species, expression of any of the constructs resulted in homogenously fluorescent forisomes that formed sieve tube plugs upon stimulation; no GFP fluorescence occurred elsewhere. Isolated fluorescent forisomes reacted to Ca(2+) and chelators by contraction and expansion, respectively, and did not lose fluorescence in the process. Wild-type forisomes showed no affinity for free GFP in vitro. The three proteins shared numerous conserved motifs between themselves and with hypothetical proteins derived from the genomes of M. truncatula, Vitis vinifera and Arabidopsis thaliana. However, they showed neither significant similarities to proteins of known function nor canonical metal-binding motifs. We conclude that ‘FOR’-like proteins are components of forisomes that are encoded by a well-defined gene family with relatives in taxa that lack forisomes. Since the mnemonic FOR is already registered and in use for unrelated genes, we suggest the acronym SEO (sieve element occlusion) for this family. The absence of binding sites for divalent cations suggests that the Ca(2+) binding responsible for forisome contraction is achieved either by as yet unidentified additional proteins, or by SEO proteins through a novel, uncharacterized mechanism. Oxford University Press 2008-11 2008-09-10 /pmc/articles/PMC2582178/ /pubmed/18784195 http://dx.doi.org/10.1093/pcp/pcn141 Text en © The Author 2008. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. The online version of this article has been published under an open access model. Users are entitled to use, reproduce, disseminate, or display the open access version of this article for non-commercial purposes provided that: the original authorship is properly and fully attributed; the Journal and the Japanese Society of Plant Physiologists are attributed as the original place of publication with the correct citation details given; if an article is subsequently reproduced or disseminated not in its entirety but only in part or as a derivative work this must be clearly indicated. For commercial re-use, please contact journals.permissions@oxfordjournals.org
spellingShingle Regular Papers
Pélissier, Hélène C.
Peters, Winfried S.
Collier, Ray
van Bel, Aart J. E.
Knoblauch, Michael
GFP Tagging of Sieve Element Occlusion (SEO) Proteins Results in Green Fluorescent Forisomes
title GFP Tagging of Sieve Element Occlusion (SEO) Proteins Results in Green Fluorescent Forisomes
title_full GFP Tagging of Sieve Element Occlusion (SEO) Proteins Results in Green Fluorescent Forisomes
title_fullStr GFP Tagging of Sieve Element Occlusion (SEO) Proteins Results in Green Fluorescent Forisomes
title_full_unstemmed GFP Tagging of Sieve Element Occlusion (SEO) Proteins Results in Green Fluorescent Forisomes
title_short GFP Tagging of Sieve Element Occlusion (SEO) Proteins Results in Green Fluorescent Forisomes
title_sort gfp tagging of sieve element occlusion (seo) proteins results in green fluorescent forisomes
topic Regular Papers
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2582178/
https://www.ncbi.nlm.nih.gov/pubmed/18784195
http://dx.doi.org/10.1093/pcp/pcn141
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