title: Environmental stresses inhibit and stimulate different protein import pathways in plant mitochondria.
abstract: The impact of various environmental stresses (drought, chilling or herbicide treatment) on the capacity of plant mitochondria to import precursor proteins was investigated. Drought treatment stimulated import and processing of various precursor proteins via the general import pathway. The stimulatory effect of drought on the general import pathway was due to an increased rate of import, was accompanied by an increased rate of processing, and could be attributed to the presequence of the precursor protein. Interestingly, drought decreased the import of the F(A)d subunit of ATP synthase suggesting a bypass of the point of stimulation during import of this precursor. Both chilling and herbicide treatment of plants, on the other hand, caused inhibition of import with all precursors tested. No decrease in processing of imported proteins was observed by these stress treatments. Western analysis of several mitochondrial proteins indicated that the steady-state level of several mitochondrial components, including the TOM20 receptor and the core subunits of the cytochrome bc(1) complex responsible for processing, remained largely unchanged. Thus environmental stresses differentially affect import of precursor proteins in a complicated manner dependent on the import pathway utilised.
authors.affiliation: Plant Molecular Biology Group, Biochemistry and Molecular Biology, School of Biomedical and Chemical Sciences, The University of Western Australia, 35 Stirling Highway, 6009, Crawley, WA, Australia.
authors.forename: Nicolas L
authors.initials: NL
authors.lastname: Taylor
authors.forename: Charlotta
authors.initials: C
authors.lastname: Rudhe
authors.forename: Joanne M
authors.initials: JM
authors.lastname: Hulett
authors.forename: Trevor
authors.initials: T
authors.lastname: Lithgow
authors.forename: Elzbieta
authors.initials: E
authors.lastname: Glaser
authors.forename: David A
authors.initials: DA
authors.lastname: Day
authors.forename: A Harvey
authors.initials: AH
authors.lastname: Millar
authors.forename: James
authors.initials: J
authors.lastname: Whelan
mesh_terms: D002736:Chloroplasts / Q000187:drug effects / Q000378:metabolism*; D003080:Cold Temperature; D004178:Diquat / Q000494:pharmacology; D004190:Disasters; D004777:Environment; D006540:Herbicides / Q000494:pharmacology*; D007700:Kinetics; D008928:Mitochondria / Q000378:metabolism*; D010269:Paraquat / Q000494:pharmacology; D018532:Pisum sativum / Q000187:drug effects / Q000378:metabolism*; D010940:Plant Proteins / Q000187:drug effects / Q000378:metabolism*; D021381:Protein Transport; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D014887:Weather
chemical_list: D006540:Herbicides; D010940:Plant Proteins; D011993:Recombinant Fusion Proteins; D004178:Diquat; D010269:Paraquat