Arabidopsis thaliana acyl-CoA-binding protein ACBP2 interacts with heavy-metal-binding farnesylated protein AtFP6

Authors


Author for correspondence:
Mee-Len Chye
Tel: +852 22990319
Fax: +852 28583477
Email: mlchye@hkucc.hku.hk

Summary

  • • Arabidopsis thaliana acyl-CoA-binding protein 2 (ACBP2) was observed to interact with farnesylated protein 6 (AtFP6), which has a metal-binding motif (M/LXCXXC). Their interaction and expression in response to heavy metals were investigated.
  • • Yeast two-hybrid analysis and in vitro assays showed that an ACBP2 derivative lacking ankyrin repeats did not interact with AtFP6, indicating that the ankyrin repeats mediate protein–protein interaction. Autofluorescence-tagged ACBP2 and AtFP6 transiently co-expressed in tobacco (Nicotiana tabacum) were both targeted to the plasma membrane.
  • • Reverse transcriptase polymerase chain reaction and northern blot analyses revealed that AtFP6 mRNA was induced by cadmium (Cd(II)) in A. thaliana roots. Assays using metal-chelate affinity chromatography demonstrated that in vitro translated ACBP2 and AtFP6 bound lead (Pb(II)), Cd(II) and copper (Cu(II)). Consistently, assays using fluorescence analysis confirmed that (His)6-AtFP6 bound Pb(II), like (His)6-ACBP2.
  • • Arabidopsis thaliana plants overexpressing ACBP2 or AtFP6 were more tolerant to Cd(II) than wild-type plants. Plasma membrane-localized ACBP2 and AtFP6 probably mediate Pb(II), Cd(II) and Cu(II) transport in A. thaliana roots. Also, (His)6-ACBP2 binds [14C]linoleoyl-CoA and [14C]linolenoyl-CoA, the precursors for phospholipid repair following lipid peroxidation under heavy metal stress at the plasma membrane. ACBP2-overexpressing plants were more tolerant to hydrogen peroxide than wild-type plants, further supporting a role for ACBP2 in post-stress membrane repair.

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