Analysis of aluminum and divalent cation binding to wheat root plasma membrane proteins using terbium phosphorescence

Journal Article · Fri Sep 01 04:00:00 EDT 1989 · Plant Physiology; (USA)

DOI:https://doi.org/10.1104/pp.91.1.233· OSTI ID:5859454

Caldwell, C R ^[1]

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1. Department of Agriculture, Beltsville, MD (USA)

A phosphorescent trivalent cation, terbium (Tb(III)), has been used to study the binding of different polyvalent cations to the proteins of wheat (Triticum aestivum L.) root plasma membranes. The phosphorescence emission intensity of Tb(III) was enhanced after Tb(III) binding to wheat root plasma membranes as a result of nonradiative resonance energy transfer from the membrane protein tyrosine and phenylalanine residues. Complex, saturable Tb(III) binding was observed, suggesting multiple binding sites. Bound Tb(III) could be displaced by divalent cations in the general order: Mn(II) > Ca(II) > Mg(II). Al(III) was very effective in reducing the protein-enhanced Tb(III) phosphorescence at pH values below 5. Al(III) also altered the Tb(III) phosphorescence lifetime, suggesting Al(III)-induced changes in membrane protein conformation. The more Al(III)-sensitive wheat cultivar (Anza) bound Al(III) with higher affinity than the more tolerant cultivar (BH 1146). At pH 5.5 where Al(III) did not displace bound Tb(III), low levels of Al(III) reduced the ability of Mn(II) to decrease Tb(III) phosphorescence. The significance of these results is discussed with respect to the mechanisms of Al(III) tolerance in wheat and the potential beneficial effects of Al(III) in reducing Mn(II) phytotoxicity.

• OSTI ID: 5859454
• Journal Information: Plant Physiology; (USA), Journal Name: Plant Physiology; (USA) Vol. 91:1; ISSN 0032-0889; ISSN PLPHA
• Country of Publication: United States
• Language: English

Related Subjects

550200* -- Biochemistry
59 BASIC BIOLOGICAL SCIENCES
ALUMINIUM
CEREALS
ELEMENTS
GRASS
LILIOPSIDA
LUMINESCENCE
MAGNOLIOPHYTA
MEMBRANES
METALS
PHOSPHORESCENCE
PHYSIOLOGY
PLANTS
RARE EARTHS
ROOTS
TERBIUM
TOXICITY
WHEAT