Responses of Plant Proteins to Heavy Metal Stress—A Review

Abstract

Plants respond to environmental pollutants such as heavy metal(s) by triggering the expression of genes that encode proteins involved in stress response. Toxic metal ions profoundly affect the cellular protein homeostasis by interfering with the folding process and aggregation of nascent or non-native proteins leading to decreased cell viability. However, plants possess a range of ubiquitous cellular surveillance systems that enable them to efficiently detoxify heavy metals toward enhanced tolerance to metal stress. As proteins constitute the major workhorses of living cells, the chelation of metal ions in cytosol with phytochelatins and metallothioneins followed by compartmentalization of metals in the vacuoles as well as the repair of stress-damaged proteins or removal and degradation of proteins that fail to achieve their native conformations are critical for plant tolerance to heavy metal stress. In this review, we provide a broad overview of recent advances in cellular protein research with regards to heavy metal tolerance in plants. We also discuss how plants maintain functional and healthy proteomes for survival under such capricious surroundings.

Ecotype-Specific Pathways of Reactive Oxygen Species Deactivation in Facultative Metallophyte Silene vulgaris (Moench) Garcke Treated with Heavy Metals

“…The last-mentioned factor seems to be particularly alarming, since the incidence of heavy metals (HMs) in the biosphere has been grown hazardously over the last several decades due to the ongoing global industrialization and urbanization [1]. Some HMs, such as zinc (Zn), nickel (Ni), or copper (Cu), are fundamental to different physiological processes and required in trace amounts for higher plants [2]. Others, like lead (Pb) and cadmium (Cd), do not have recognized beneficial roles, although more and more research has recently indicated their positive effects on morpho-physiological traits under low-dose treatment [3][4][5][6].…”

Expression of Genes Involved in Heavy Metal Trafficking in Plants Exposed to Salinity Stress and Elevated Cd Concentrations

“…In addition to CAXs, the C subfamily of the ATPase binding cassette (ABCC) has been recognized as an additional vacuolar metal-PC transporter. Although it has been reported that vacuolar sequestration of Cd by ABCC is essential for its complete detoxification, transporters from this subfamily are also involved in the transport of such ions as Zn, Cu, Mn and Fe [16]. Apart from these strategies, the translocation of Cd to remote organs, combined with sequestration in tissues not involved in vital metabolic processes, seems to play a crucial role in Cd tolerance.…”

Impact of Essential Micronutrient, Zn, on Growth and Chlorophyll Biosynthesis in Young <i>Zea mays</i> Seedlings

“…It seems that enhanced protein and proline synthesis is associated with Zn effects in root, as these contents are significantly increased. Increased levels of protein may be required for the synthesis of stress induced proteins [20] and of proline, for osmotic adjustments in response to Zn.…”