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N-Terminal Cys-Rich Region of a Rice Type 1 Metallothionein Independently Forms Metal-Thiolate Cluster

[ Vol. 23 , Issue. 7 ]

Author(s):

Soheila Ahmadi and Azar Shahpiri   Pages 639 - 644 ( 6 )

Abstract:


The members of plant metallothionein (MT) subfamily p1 are characterized with the presence of six Cys at each end of N- and C-terminal of their amino acid sequences which are arranged in a CXCXXXCXCXXXCXC and CXCXXXCXCXXCXC sequence, respectively. In this study we evaluated the independence of N-terminal Cys-rich region of a type 1 MT isoform from rice (OsMTI- 1b) in forming metal-thiolate cluster. To this end the N-terminal of OsMTI-1b (N-OsMTI-1b) was heterologously expressed in Escherichia coli as fusion protein with glutathione-S-transferase (GST). The E.coli cells expressing GST-N-OsMTI-1b were able to remove Cd2+ and Ni2+ from culture medium. The recombinant GST-N-OsMTI-1b was purified using affinity chromatography. The UV absorption spectra recorded after the reconstitution of the apo-protein with Cd2+ and Ni2+ confirmed that GST-N-OsMTI-1b was able to form complexes with Cd2+ and Ni2+. These results demonstrate the formation of independent metal-thiolate cluster at Nterminal Cys-rich region of GST-N-OsMTI-1b without participation of C-terminal Cys-rich region.

Keywords:

Metallothionein, Metal-thiolate cluster, N-terminal Cys-rich region, OsMTI-1b, Rice.

Affiliation:

Department of Biotechnology, College of Agriculture, Isfahan University of Technology, Isfahan 84156- 83111, Iran.

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