Characterization of a selenium-resistance-enhancing homocysteine S-methyltransferase from Aegilops tauschii

Wu, L.J. and Shang, Y. and Liu, T. and Chen, W.J. and Liu, B.L. and Zhang, L.Q. and Liu, D.C. and Zhang, B. and Zhang, H.G. (2018) Characterization of a selenium-resistance-enhancing homocysteine S-methyltransferase from Aegilops tauschii. Cereal Research Communications, 46 (2). pp. 263-274. ISSN 0133-3720

Preview

Text 0806.46.2018.08.pdf Download (339kB) | Preview

Abstract

In this study, the cDNA of homocysteine S-methyltransferase was isolated from Aegilops tauschii Coss., with the gene accordingly designated as AetHMT1. Similar to other methyltransferases, AetHMT1 contains a GGCCR consensus sequence for a possible zinc-binding motif near the C-terminal and a conserved cysteine residue upstream of the zinc-binding motif. Analysis of AetHMT1 uncovered no obvious chloroplast or mitochondrial targeting sequences. We functionally expressed AetHMT1 in Escherichia coli and confirmed its biological activity, as evidenced by a positive HMT enzyme activity of 164.516 ± 17.378 nmol min⁻¹ mg⁻¹ protein when catalyzing the transformation of L-homocysteine. Compared with the bacterium containing the empty vector, E. coli harboring the recombinant AetHMT1 plasmid showed much higher tolerance to selenate and selenite. AetHMT1 transcript amounts in different organs were increased by Na₂SeO₄ treatment, with roots accumulating higher amounts than stems, old leaves and new leaves. We have therefore successfully isolated HMT1 from Ae. tauschii and characterized the biochemical and physiological functions of the corresponding protein.

Actions (login required)

Edit Item