Distinctive expression of a zinc-binding protein in rice callus grown in medium with high zinc concentration |
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| Authors: | Yuichi Saeki Ayako Yasukouchi Yoshitaka Nagatomo Hiroshi Takaki |
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| Institution: | Department of Agriculture and Forest Science, Faculty of Agriculture , Miyazaki University , Miyazaki , 889-2192 , Japan |
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| Abstract: | We investigated the growth, contents of water-soluble protein and free amino acids of the callus of japonica rice (Oryza sativa L. cv. Nipponbare) cultured in liquid N6 medium containing a high concentration of zinc. Furthermore, we determined the N-terminal amino acid sequence of a Zn-binding protein expressed in large quantities in the callus. The addition of Zn stimulated the growth of the callus and increased the Zn concentration. The callus subjected to the high-Zn treatment (hereafter referred to as CHZn) contained a larger amount of soluble proteins and a smaller amount of free amino acids than the control callus. Zinc-binding proteins were separated by affinity chromatography. The SDS-PAGE pattern of these proteins showed a distinctive protein band of about 29 kDa. Especially, CHZn contained larger quantities of 29 kDa protein than the control callus. Twenty-seven N-terminal amino acids of the protein were sequenced as DYAPMTLTIVNNCPYPVWPGIQANSGH. Results of homology search to the amino acid sequences from the nr-aa database and the dbEST database suggested that this 29 kDa protein may be a novel zinc-binding protein and that the protein may regulate the concentration of free zinc in the cytoplasm of callus cells through its binding to zinc ions. |
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| Keywords: | metallothionein-like protein N6 medium Oryza sativa L rice callus zinc-binding protein |
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