title: The membrane-bound respiratory chain of Pseudomonas pseudoalcaligenes KF707 cells grown in the presence or absence of potassium tellurite.
abstract: The respiratory chain of Pseudomonas pseudoalcaligenes KF707 in membranes isolated from cells grown in the presence or absence of the toxic oxyanion tellurite (TeO3(2-)) was examined. Aerobic growth in the absence of tellurite shows an NADH-dependent respiration which is 80% catalysed by the cytochrome (cyt) bc1-containing pathway leading to two terminal membrane-bound cyt c oxidases inhibited by different concentrations of KCN (IC50 0.2 and 1 microM). A third oxidase, catalysing the remaining 20% of the cyanide-resistant respiration and fully inhibited by 2-3 mM KCN, is also present; this latter pathway accounts for 60-70% of the total NADH-dependent respiration in membranes from cells grown in LB medium supplemented with potassium tellurite (35 microg x ml(-1)). Two high-potential b-type haems (E(m,7) +395 and 318 mV) are redox centres of a membrane-bound cyt c oxidase (possibly of the cbb3 type) which shows a 50% decrease of its activity in parallel with a similar decrease of the c-type haem content (mostly soluble cyt c) in membranes from tellurite-grown cells; the latter type of cells specifically contain a cyt b type at +203 mV (pH 9.0) which is likely to be involved in cyanide-resistant respiration. Comparison of the growth curve of KF707 cells in parallel with tellurite uptake showed that intracellular accumulation of tellurium (Te(0)) crystallites starts from the mid-exponential growth phase, whereas tellurite-induced changes of the respiratory chain are already evident during the early stages of growth. These data were interpreted as showing that reduction of tellurite to tellurium and tellurite-dependent modifications of the respiratory chain are unrelated processes in P. pseudoalcaligenes KF707.
authors.affiliation: Department of Biology, University of Bologna, 42 Irnerio, 40126 Bologna I, Italy1.
authors.forename: Giovanna
authors.initials: G
authors.lastname: Di Tomaso
authors.affiliation: Department of Biology, University of Bologna, 42 Irnerio, 40126 Bologna I, Italy1.
authors.forename: Stefano
authors.initials: S
authors.lastname: Fedi
authors.affiliation: Department of Biology, University of Bologna, 42 Irnerio, 40126 Bologna I, Italy1.
authors.forename: Monica
authors.initials: M
authors.lastname: Carnevali
authors.affiliation: Department of Biology, University of Bologna, 42 Irnerio, 40126 Bologna I, Italy1.
authors.forename: Marco
authors.initials: M
authors.lastname: Manegatti
authors.affiliation: Department of Biology, University of Bologna, 42 Irnerio, 40126 Bologna I, Italy1.
authors.forename: Carlo
authors.initials: C
authors.lastname: Taddei
authors.affiliation: Department of Biology, University of Bologna, 42 Irnerio, 40126 Bologna I, Italy1.
authors.forename: Davide
authors.initials: D
authors.lastname: Zannoni
mesh_terms: D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism*; D003470:Culture Media / Q000737:chemistry / Q000494:pharmacology; D003574:Cytochrome c Group / Q000032:analysis / Q000378:metabolism; D004579:Electron Transport / Q000187:drug effects; D007700:Kinetics; D010084:Oxidation-Reduction; D011199:Potentiometry; D011549:Pseudomonas / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism* / Q000648:ultrastructure; D013691:Tellurium / Q000378:metabolism* / Q000494:pharmacology
chemical_list: D003470:Culture Media; D003574:Cytochrome c Group; C026899:potassium tellurate(IV); D013691:Tellurium