Desiccation and Zinc Binding Induce Transition of Tomato Abscisic Acid Stress Ripening 1, a Water Stress- and Salt Stress-Regulated Plant-Specific Protein, from Unfolded to Folded State

Abstract

Abscisic acid stress ripening 1 (ASR1) is a low molecular weight plant-specific protein encoded by an abiotic stress-regulated gene. Overexpression of ASR1 in transgenic plants increases their salt tolerance. The ASR1 protein possesses a zinc-dependent DNA-binding activity. The DNA-binding site was mapped to the central part of the polypeptide using truncated forms of the protein. Two additional zinc-binding sites were shown to be localized at the amino terminus of the polypeptide. ASR1 protein is presumed to be an intrinsically unstructured protein using a number of prediction algorithms. The degree of order of ASR1 was determined experimentally using nontagged recombinant protein expressed in Escherichia coli and purified to homogeneity. Purified ASR1 was shown to be unfolded using dynamic light scattering, gel filtration, microcalorimetry, circular dichroism, and Fourier transform infrared spectrometry. The protein was shown to be monomeric by analytical ultracentrifugation. Addition of zinc ions resulted in a global change in ASR1 structure from monomer to homodimer. Upon binding of zinc ions, the protein becomes ordered as shown by Fourier transform infrared spectrometry and microcalorimetry, concomitant with dimerization. Tomato (Solanum lycopersicum) leaf soluble ASR1 is unstructured in the absence of added zinc and gains structure upon binding of the metal ion. The effect of zinc binding on ASR1 folding and dimerization is discussed.

Rice ASR1 Protein with Reactive Oxygen Species Scavenging and Chaperone-like Activities Enhances Acquired Tolerance to Abiotic Stresses in Saccharomyces cerevisiae

“…As seen in yeast, the over-expression of the ASR protein increases stress tolerance in several plants (Goldgur et al, 2007). For example, over-expression of tomato ASR1 and lily ASR increases salt tolerance in tobacco (Kalifa, 2004) and Arabidopsis (Yang et al, 2005), respectively.…”

“…Among ASR proteins, ASR1 is a plant-specific, highly charged low molecular weight and heat-stable protein whose expression in plants is induced by high salinity, dehydration, and treatment with the plant hormone ABA (Goldgur et al, 2007). The molecular mechanism behind its biological activity cannot be simply deduced based on sequence homology with other known proteins.…”

“…Low accumulation of ASR1 mRNA and its protein product has been detected in the roots and shoots of irrigated tomato plants. However, following NaCl, polyethylene glycol (PEG) or ABA treatment, a rapid increase in ASR1 levels occurs (Goldgur et al, 2007). In addition, up-regulation of an ASR1 homolog was also observed in the roots of salt-stressed maize plants.…”

The mutual responses of higher plants to environment: Physiological and microbiological aspects

“…Plant production realization is obtained eventually through physiological pathways at least at the level of individual and community [102][103][104][105][106][107][108][109]120,[130][131][132][133][134][135][136][137][138][139][140]. One molecule or cell cannot produce any economic effect in field [22,23,77,78,117].…”

“…In the wide field of plant biology, its core is the study for life activities at molecular level, whose interactions at various soil-root biointerfaces at different scales are quite important to keep a steady state between plants and changing environment, especially adverse surroundings. In practice, the key point to agriculture is how to regulate the harmonious relationship between soil-environment and crops and make the best of physiological potential of crops [137][138][139][140][141][142][143][144][145][146][147]. So, adaptation in plants is an important topic in basic and applied biology under global climate change [11,[15][16][17][18][19][43][44][45][46][47][48][104][105][106][107]120].…”