Functional reconstitution of Arabidopsis thaliana plant uncoupling mitochondrial protein (AtPUMP1) expressed in Escherichia coli

The Arabidopsis thaliana uncoupling protein (UCP) gene was expressed in Esc herichia coli and isolated protein reconstituted into liposomes. Linoleic a cid-induced H+ fluxes were sensitive to purine nucleotide inhibition with a n apparent K-i (in mM) of 0.8 (GDP), 0.85 (ATP), 0.98 (GTP), and 1.41 (ADP) ; the inhibition was pH-dependent. Kinetics of AtPUMP1-mediated H+ fluxes w ere determined for lauric, myristic, palmitic, oleic, linoleic, and linolen ic acids. Properties of recombinant AtPUMP1 indicate that it represents a p lant counterpart of animal UCP2 or UCP3. This work brings the functional an d genetic approaches together for the first time, providing strong support that AtPUMP1 is truly an UCP. (C) 2001 Published by Elsevier Science B.V. o n behalf of the Federation of European Biochemical Societies.