The N-terminal degenerated metal-binding domain is involved in the heavy metal transport activity of TaHMA2

• Published in: Plant cell reports 2015-09, Vol.34 (9), p.1615-1628
• Main Authors: Xiang, Shuqin, Feng, Shanshan, Zhang, Yuxiu, Tan, Jinjuan, Liang, Shuang, Chai, Tuanyao
• Format: Article
• Language: English
• Subjects: Amino Acid Motifs; Amino Acid Sequence; Arabidopsis thaliana; Biological Transport; Biomedical and Life Sciences; Biotechnology; Cadmium; Cadmium - toxicity; Cell Biology; Cell Membrane - metabolism; Heavy metals; Life Sciences; Metals, Heavy - metabolism; Molecular Sequence Data; Nicotiana tabacum; Original Paper; Oryza sativa; Plant Biochemistry; Plant Proteins - chemistry; Plant Proteins - metabolism; Plant Sciences; Protein Structure, Tertiary; Protein Transport; Saccharomyces cerevisiae; Saccharomyces cerevisiae - cytology; Saccharomyces cerevisiae - metabolism; Sequence Alignment; Spectrophotometry, Atomic; Structure-Activity Relationship; Subcellular Fractions - metabolism; Translocation; Triticum - metabolism; Triticum aestivum; Wheat; Yeasts
• ISSN: 0721-7714; 1432-203X
• DOI: 10.1007/s00299-015-1813-x

Key message We identified key residues of TaHMA2, and the N- and C-terminal regions of the protein have different roles in its transport function when heterologously expressed in yeast. TaHMA2, a P 1B -type ATPase from wheat ( Triticum aestivum L.), plays an important role in heavy metal homeostasis in plants. A previous study showed that overexpressing TaHMA2 in rice ( Oryza sativa L.), Arabidopsis thaliana , or tobacco ( Nicotiana tabacum L.) resulted in various responses to heavy metals. Here, we report the heterologous expression of TaHMA2 in the yeast Saccharomyces cerevisiae . TaHMA2 expression increased the yeast’s sensitivity to Cd, but not to Zn, Pb or Co, and increased Cd accumulation was concurrently observed. The eGFP-TaHMA2 fusion protein was localized to the plasma membrane and showed a discontinuous pattern. Mutagenesis of the cysteine and glutamate residues in the N-terminal metal-binding domain (N-MBD) impaired the function of TaHMA2. Deletion of most of the C terminus (TaHMA2ΔC, 712–1003) partially abolished the protein’s function, whereas deletion of the N terminus (TaHMA2ΔN, 2–699) completely abolished Cd sensitivity. These data suggest that cysteine and glutamate residues are important for the metal-binding/translocation function of TaHMA2. Additional studies are needed to further understand the selectivity of TaHMA2 in planta .