Synthesis of a bifunctional metallothionein/beta-glucuronidase fusion protein in transgenic tobacco plants as a means of reducing leaf cadmium levels.
Chimeric genes under the control of a CaMV 35S promoter with a doubled enhancer (35S2) that encode a mammalian metallothionein (hMTII), or an Escherichia coli beta-glucuronidase (GUS), or a hMTII/GUS fusion protein were introduced into the genome of tobacco (Nicotiana tabacum cv. PBD6). Transcripts and Cd-binding proteins of expected size were observed in plants expressing either the 35S2-hMTII or the 35S2-hMTII/GUS gene, and in the latter plants a protein with GUS activity that was larger than the native GUS enzyme was observed. Thus, plants expressing the hMTII-GUS gene synthesize a bifunctional protein, with both GUS and Cd-binding activity. In an in vitro assay, seedlings expressing either one of these genes had 60-70% lower Cd concentration in their shoots than controls, and Cd translocation to the shoot system was reduced (approximately 20% of Cd absorbed was translocated), compared with that in controls expressing a 35S2-GUS gene, where approximately 50% of the Cd absorbed was translocated.
Elmayan
T
T
Laboratoire de Biologie Cellulaire, INRA-Versailles, France.
Tepfer
M
M
D015152:Blotting, Northern; D002104:Cadmium / Q000032:analysis*; D005966:Glucuronidase / Q000096:biosynthesis*; D008668:Metallothionein / Q000096:biosynthesis*; D018515:Plant Leaves / Q000737:chemistry*; D030821:Plants, Genetically Modified / Q000737:chemistry* / Q000378:metabolism; D010947:Plants, Toxic; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis*; D014026:Nicotiana / Q000737:chemistry / Q000378:metabolism
D011993:Recombinant Fusion Proteins; D002104:Cadmium; D008668:Metallothionein; D005966:Glucuronidase