Expression of a truncated tobacco NtCBP4 channel in transgenic plants and disruption of the homologous Arabidopsis CNGC1 gene confer Pb2+ tolerance.
Recently we reported on a plasma membrane tobacco protein (designated NtCBP4) that binds calmodulin. When overexpressed in transgenic plants, NtCBP4 confers Pb2+ hypersensitivity associated with enhanced accumulation of this toxic metal. To further investigate possible modulation of Pb2+ tolerance in plants, we prepared transgenic plants that express a truncated version of this protein (designated NtCBP4DeltaC) from which its C-terminal, with the calmodulin-binding domain and part of the putative cyclic nucleotide-binding domain, was removed. In contrast to the phenotype of transgenic plants expressing the full-length gene, transgenic plants expressing the truncated gene showed improved tolerance to Pb2+, in addition to attenuated accumulation of this metal. Furthermore, disruption by T-DNA insertion mutagenesis of the Arabidopsis CNGC1 gene, which encodes a homologous protein, also conferred Pb2+ tolerance. We suggest that NtCBP4 and AtCNGC1 are components of a transport pathway responsible for Pb2+ entry into plant cells.
Sunkar
R
R
Department of Plant Sciences, The Weizmann Institute of Science, Rehovot 76100, Israel.
Kaplan
B
B
Bouché
N
N
Arazi
T
T
Dolev
D
D
Talke
I N
IN
Maathuis
F J
FJ
Sanders
D
D
Bouchez
D
D
Fromm
H
H
D000222:Adaptation, Physiological / Q000235:genetics; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics*; D001483:Base Sequence; D002148:Calmodulin-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D054815:Cyclic Nucleotide-Gated Cation Channels; D004305:Dose-Response Relationship, Drug; D018506:Gene Expression Regulation, Plant; D015151:Immunoblotting; D007473:Ion Channels / Q000235:genetics*; D007854:Lead / Q000378:metabolism / Q000633:toxicity*; D008969:Molecular Sequence Data; D009154:Mutation; D063245:Plant Development; D010940:Plant Proteins; D010944:Plants / Q000187:drug effects / Q000235:genetics; D030821:Plants, Genetically Modified; D010947:Plants, Toxic; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D014026:Nicotiana / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development
C402668:CBP4 protein, Nicotiana tabacum; D002148:Calmodulin-Binding Proteins; D054815:Cyclic Nucleotide-Gated Cation Channels; D007473:Ion Channels; D010940:Plant Proteins; D012333:RNA, Messenger; D007854:Lead