Tailed Forisomes of Canavalia gladiata: A New Model to Study Ca2+-driven Protein Contractility

W. S Peters; M Knoblauch; S. A Warmann; R Schnetter; A. Q Shen; W. F Pickard

doi:10.1093/aob/mcm080

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Tailed Forisomes of Canavalia gladiata: A New Model to Study Ca2+-driven Protein Contractility

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Tailed Forisomes of Canavalia gladiata: A New Model to Study Ca2+-driven Protein Contractility

W. S Peters, M Knoblauch, S. A Warmann, R Schnetter, A. Q Shen and W. F Pickard

Annals of botany, Vol.100(1), pp.101-109

07/2007

DOI: https://doi.org/10.1093/aob/mcm080

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https://hdl.handle.net/2376/108533

PMCID: PMC2735297

PMID: 17584851

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Abstract

phloem transport

forisome geometry

contractile protein

fabaceae

contraction kinetics

dependent contractility

tailed forisome

sieve element

Background and Aims Forisomes are Ca2+-dependent contractile protein bodies that form reversible plugs in sieve tubes of faboid legumes. Previous work employed Vicia faba forisomes, a not entirely unproblematic experimental system. The aim of this study was to seek to establish a superior model to study these intriguing actuators. Methods Existing isolation procedures were modified to study the exceptionally large, tailed forisomes of Canavalia gladiata by differential interference contrast microscopy in vitro. To analyse contraction/expansion kinetics quantitatively, a geometric model was devised which enabled the computation of time-courses of derived parameters such as forisome volume from simple parameters readily determined on micrographs. Key Results Advantages of C. gladiata over previously utilized species include the enormous size of its forisomes (up to 55 µm long), the presence of tails which facilitate micromanipulation of individual forisomes, and the possibility of collecting material repeatedly from these fast-growing vines without sacrificing the plants. The main bodies of isolated Canavalia forisomes were box-shaped with square cross-sections and basically retained this shape in all stages of contraction. Ca2+-induced a 6-fold volume increase within about 10-15 s; the reverse reaction following Ca2+-depletion proceeded in a fraction of that time. Conclusions The sword bean C. gladiata provides a superior experimental system which will prove indispensable in physiological, biophysical, ultrastructural and molecular studies on the unique ATP-independent contractility of forisomes.

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Title: Tailed Forisomes of Canavalia gladiata: A New Model to Study Ca2+-driven Protein Contractility
Creators: W. S Peters - 1 Indiana University/Purdue University, Department of Biology, 2101 East Coliseum Boulevard, Fort Wayne, IN 46805-1499, USA
M Knoblauch - 2 School of Biological Science, Washington State University, Pullman, WA 99164-4236, USA
S. A Warmann - 3 Department of Mechanical and Aerospace Engineering, Washington University, St Louis, MO 63130, USA
R Schnetter - 4 Institut für Allgemeine Botanik, Justus-Liebig-Universität, Senckenbergstr. 17-21, D-35390 Gießen, Germany
A. Q Shen - 3 Department of Mechanical and Aerospace Engineering, Washington University, St Louis, MO 63130, USA
W. F Pickard - 5 Department of Electrical and Systems Engineering, Washington University, St Louis, MO 63130, USA
Publication Details: Annals of botany, Vol.100(1), pp.101-109
Academic Unit: Biological Sciences, School of
Publisher: Oxford University Press
Identifiers: 99900547147301842
Language: English
Resource Type: Journal article