ZmPUMP encodes a fully functional monocot plant uncoupling mitochondrial protein whose affinity to fatty acid is increased with the introduction of a His pair at the second matrix loop
- Instituto de Biociencias, Departamento de Genetica, UNESP, Botucatu, SP (Brazil)
- Laboratorio de Bioenergetica, Faculdade de Ciencias Medicas (NMCE), UNICAMP, Campinas, SP (Brazil)
Uncoupling proteins (UCPs) are specialized mitochondrial transporter proteins that uncouple respiration from ATP synthesis. In this study, cDNA encoding maize uncoupling protein (ZmPUMP) was expressed in Escherichia coli and recombinant ZmPUMP reconstituted in liposomes. ZmPUMP activity was associated with a linoleic acid (LA)-mediated H{sup +} efflux with K {sub m} of 56.36 {+-} 0.27 {mu}M and V {sub max} of 66.9 {mu}mol H{sup +} min{sup -1} (mg prot){sup -1}. LA-mediated H{sup +} fluxes were sensitive to ATP inhibition with K {sub i} of 2.61 {+-} 0.36 mM (at pH 7.2), a value similar to those for dicot UCPs. ZmPUMP was also used to investigate the importance of a histidine pair present in the second matrix loop of mammalian UCP1 and absent in plant UCPs. ZmPUMP with introduced His pair (Lys155His and Ala157His) displayed a 1.55-fold increase in LA-affinity while its activity remained unchanged. Our data indicate conserved properties of plant UCPs and suggest an enhancing but not essential role of the histidine pair in proton transport mechanism.
- OSTI ID:
- 20798967
- Journal Information:
- Biochemical and Biophysical Research Communications, Vol. 344, Issue 1; Other Information: DOI: 10.1016/j.bbrc.2006.03.132; PII: S0006-291X(06)00665-6; Copyright (c) 2006 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0006-291X
- Country of Publication:
- United States
- Language:
- English
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