Two Novel Intrinsic Annexins Accumulate in Wheat Membranes in Response to Low Temperature

Abstract

Four immunologically related proteins that belong to the annexin family were identified in cold acclimated wheat (Triticum aestivum). Two soluble forms with molecular masses of 34 and 36 kDa were found to bind phospholipid membranes in a calcium-dependent manner. These two forms are similar to the previously reported doublet in several plant species. The other two forms, with molecular masses of 39 and 22.5 kDa, were found associated with the microsomal fraction. Biochemical analysis showed that both forms are intrinsic membrane proteins and their association with the membrane is calcium independent. This is, to our knowledge, the first report of the presence of these annexin forms in plants. Membrane purification by two phase partitioning demonstrated that the p39 form is localized to the plasma membrane. Immunoblot analysis showed that the protein level of both p39 and p22.5 increases gradually reaching a maximum level after one day of low temperature exposure. The protein accumulation was similar in both hardy and less hardy cultivars, suggesting that the accumulation is not correlated with freezing tolerance. The results are discussed with respect to the possible role of these new intrinsic membrane annexins in low temperature signal transduction pathway.

AtBAG7 , an Arabidopsis Bcl-2–associated athanogene, resides in the endoplasmic reticulum and is involved in the unfolded protein response

“…To circumvent this damage, plant membranes, particularly the plasma membrane, undergo structural changes including the accumulation of mono-or diunsaturated species of phosphatidylcholine which increase cryostability (44,45). Plasma membrane proteins may play an important role during cold acclimation (46)(47)(48). A recent study by Kawamura and Uemura (33) identified substantial changes in the protein content for range of plasma membrane proteins during the early stages of cold acclimation.…”

Zea mays Annexins Modulate Cytosolic Free Ca2+ and Generate a Ca2+-Permeable Conductance

“…In its extracellular form, the channel-forming annexin ANXA5 regulates Polycystin-1 (a transient receptor potential channel) at its extracellular N terminus (Markoff et al, 2007), while extracellular ANXA1 causes [Ca 2+ ] cyt increase by activating plasma membrane G-protein-coupled receptors (Babbin et al, 2006). Generally, the known abundance of annexins in the cytosol and their ability to relocate to plasma and endomembranes (Thonat et al, 1997;Breton et al, 2000;Lee et al, 2004;reviewed in Mortimer et al, 2008) place them predominantly as intracellular regulators of [Ca 2+ ] cyt . In this respect, annexins, as regulators of plant channels, can be viewed as being similar to calmodulin.…”

“…Maize (Zea mays) annexins have been found to stimulate Ca 2+ -dependent exocytosis in root cap cells (Carroll et al, 1998), the process underlying cell expansion and plant growth (Carroll et al, 1998). Annexin relocation from the cytosol to membranes can occur in response to specific stimuli, such as touch (Thonat et al, 1997), cold (Breton et al, 2000), and salinity , suggesting a role in adaptive signaling. Indeed, Arabidopsis thaliana annexin 1 (ANN1) expression is upregulated by peroxide, salicylic acid (Gidrol et al, 1996), abscisic acid , drought, cold, and salt stress (Cantero et al, 2006).…”

Low Temperature Promotes Annexin V Expression in Newt Testis

“…In wheat, 39 kDa and 25 kDa annexins were induced in response to low temperatures during cold acclimation (Breton et al ., 2000). These results suggest that several types of annexins are temperature-sensitive proteins.…”

“…In wheat, novel annexin expressions are induced by low temperatures during cold acclimation (Breton et al ., 2000). These results suggest that the annexin family proteins may be new members of the stress protein family.…”