title: Non-haem iron and the dissociation of piericidin A sensitivity from site 1 energy conservation in mitochondria from Torulopsis utilis.
abstract: 1. The aerobic incubation of iron-deficient Torulopsis utilis cells for 12h under non-growing conditions results in the recovery by mitochondria of the previously absent site 1 energy conservation and sensitivity to piericidin A. 2. The recovery of piericidin A sensitivity but not site 1 is prevented by the presence of cycloheximide (100mug/ml) in the medium used for aerobic incubation of the cells. Rotenone sensitivity behaved similarly. 3. Chloramphenicol, erythromycin and tetracycline were without effect on the recovery of site 1 and piericidin A sensitivity. 4. Inclusion of (59)Fe in the growth medium can be used as the basis for a highly sensitive assay for non-haem iron. 5. Iron-limited growth of T. utilis lowers the concentration of both non-haem iron and acid-labile sulphide of submitochondrial particles by over 20-fold compared with the ;normal' situation with iron-supplemented glycerol-limited growth. 6. Increases in the non-haem iron and acid-labile sulphide concentrations of submitochondrial particles occur when site 1 and piericidin A sensitivity are recovered. The increase is approximately halved by the presence of cycloheximide. 7. The non-haem iron of T. utilis submitochondrial particles does not exchange with added iron. 8. Continuous culture of T. utilis at the transition between glycerol- and iron-limitation results in cells where mitochondria possess site 1 energy conservation but lack piericidin A sensitivity. 8. It is concluded, in contrast with widely held views to the opposite, that energy conservation at site 1 does not require electron flow to proceed through a piericidin A- or rotenone-sensitive route. 9. Restriction of the iron supplied to growing T. utilis to a concentration just above that required for growth limitation demonstrates that a 10- to 20-fold decrease of the ;normal' non-haem iron concentration of both cells and mitochondria is without effect on the growth yield per unit of carbon source. Submitochondrial particles prepared from such iron-restricted but otherwise functionally normal cells have a non-haem iron concentration of about 0.5-0.8ng-atom/mg of protein. It is concluded that the concentration of iron-sulphur protein required for normal function by the respiratory chain is close to the concentrations of cytochromes and flavoproteins.
mesh_terms: D002701:Chloramphenicol / Q000494:pharmacology; D003513:Cycloheximide / Q000494:pharmacology; D003580:Cytochromes; D004579:Electron Transport; D004735:Energy Transfer; D004917:Erythromycin / Q000494:pharmacology; D005420:Flavoproteins; D005990:Glycerol; D006418:Heme; D007501:Iron / Q000378:metabolism*; D007503:Iron Isotopes; D008293:Malates / Q000378:metabolism; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D003904:Mitosporic Fungi / Q000378:metabolism*; D009243:NAD; D010101:Oxygen Consumption; D011506:Proteins; D011725:Pyridines / Q000378:metabolism*; D011773:Pyruvates / Q000378:metabolism; D012402:Rotenone / Q000494:pharmacology; D013455:Sulfur; D013752:Tetracycline / Q000494:pharmacology; D013997:Time Factors
chemical_list: D003580:Cytochromes; D005420:Flavoproteins; D007503:Iron Isotopes; D008293:Malates; D011506:Proteins; D011725:Pyridines; D011773:Pyruvates; D012402:Rotenone; D009243:NAD; D006418:Heme; D004917:Erythromycin; D002701:Chloramphenicol; D013455:Sulfur; D003513:Cycloheximide; D007501:Iron; D013752:Tetracycline; D005990:Glycerol