title: The activity of plant inner membrane anion channel (PIMAC) can be performed by a chloride channel (CLC) protein in mitochondria from seedlings of maize populations divergently selected for cold tolerance.
abstract: The proteins performing the activity of the inner membrane anion channel (IMAC) and its plant counterpart (PIMAC) are still unknown. Lurin et al. (Biochem J 348: 291-295, 2000) indicated that a chloride channel (CLC) protein corresponds to PIMAC activity in tobacco seedling mitochondria. In this study, we investigated: (i) the presence of a CLC protein in maize seedling mitochondria; (ii) the involvement of this protein in plant cold tolerance; and (iii) its possible role in PIMAC activity. We validated the presence of a CLC protein (ZmCLCc) in maize mitochondria by immunoassay using a polyclonal antibody against its C-terminus. The differential expression of the ZmCLCc protein in mitochondria was measured in seedlings of maize populations divergently selected for cold tolerance and grown at different temperatures. The ZmCLCc protein level was higher in cold stressed than in non-stressed growing conditions. Moreover, the ZmCLCc level showed a direct relationship with the cold sensitivity level of the populations under both growing conditions, suggesting that selection for cold tolerance induced a constitutive change of the ZmCLCc protein amount in mitochondria. The anti-ZmCLCc antibody inhibited (about 60%) the channel-mediated anion translocations by PIMAC, whereas the same antibody did not affect the free diffusion of potassium thiocyanide through the inner mitochondrial membrane. For this reason, we conclude that the mitochondrial ZmCLCc protein can perform the PIMAC activity in maize seedlings.
authors: Laboratory of Plant Physiology, Dipartimento di Scienze del Mare, Università Politecnica delle Marche, Via Brecce Bianche, 60123, Ancona, Italy.
authors: Elisabetta
authors: E
authors: Tampieri
authors: Elena
authors: E
authors: Baraldi
authors: Francesco
authors: F
authors: Carnevali
authors: Elisabetta
authors: E
authors: Frascaroli
authors: Aurelio
authors: A
authors: De Santis
mesh_terms: D000064:Acclimatization / Q000502:physiology*; D018118:Chloride Channels / Q000378:metabolism*; D003080:Cold Temperature; D008928:Mitochondria / Q000378:metabolism*; D051336:Mitochondrial Membranes / Q000378:metabolism*; D010940:Plant Proteins / Q000378:metabolism*; D036226:Seedlings / Q000254:growth & development / Q000378:metabolism*; D014026:Nicotiana / Q000254:growth & development / Q000378:metabolism; D003313:Zea mays
chemical_list: D018118:Chloride Channels; D010940:Plant Proteins