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Titolo:
An unusual cytochrome o '-type cytochrome c oxidase in a Bacillus cereus cytochrome a(3) mutant has a very high affinity for oxygen
Autore:
Contreras, ML; Escamilla, JE; Del Arenal, IP; Davila, JR; Dmello, R; Poole, RK;
Indirizzi:
Univ Sheffield, Krebs Inst Biomolec Res, Dept Mol Biol & Biotechnol, Sheffield S10 2TN, S Yorkshire, England Univ Sheffield Sheffield S Yorkshire England S10 2TN S Yorkshire, England Natl Autonomous Univ Mexico, Fac Med, Inst Fisiol Celular, Mexico City 04510, DF, Mexico Natl Autonomous Univ Mexico Mexico City DF Mexico 04510 04510, DF, Mexico Natl Autonomous Univ Mexico, Fac Med, Dept Bioquim, Mexico City 04510, DF,Mexico Natl Autonomous Univ Mexico Mexico City DF Mexico 04510 04510, DF,Mexico Univ Autonoma Puebla, Escuela Biol, Puebla 72570, Mexico Univ Autonoma Puebla Puebla Mexico 72570 uela Biol, Puebla 72570, Mexico Univ London Imperial Coll Sci Technol & Med, Sch Med, Dept Paediat, LondonW2 1PG, England Univ London Imperial Coll Sci Technol & Med London England W2 1PG ngland
Titolo Testata:
MICROBIOLOGY-UK
, volume: 145, anno: 1999,
parte:, 7
pagine: 1563 - 1573
SICI:
1350-0872(199907)145:<1563:AUCO'C>2.0.ZU;2-I
Fonte:
ISI
Lingua:
ENG
Soggetto:
THERMOPHILIC BACTERIUM PS3; CARBON-MONOXIDE-BINDING; ESCHERICHIA-COLI; HEME-A; TERMINAL OXIDASES; AZOTOBACTER-VINELANDII; QUINOL OXIDASE; SUBTILIS; COPPER; BO;
Keywords:
Bacillus cereus; cytochrome o '-like oxidase; cytochrome aa(3); oxygen affinity; sporulation;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
42
Recensione:
Indirizzi per estratti:
Indirizzo: Poole, RK Univ Sheffield, Krebs Inst Biomolec Res, Dept Mol Biol & Biotechnol, Sheffield S10 2TN, S Yorkshire, England Univ Sheffield Sheffield S Yorkshire England S10 2TN e, England
Citazione:
M.L. Contreras et al., "An unusual cytochrome o '-type cytochrome c oxidase in a Bacillus cereus cytochrome a(3) mutant has a very high affinity for oxygen", MICROBIO-UK, 145, 1999, pp. 1563-1573

Abstract

Bacillus cereus strain PYM1 is a mutant unable to synthesize haem A or spectrally detectable cytochromes aa(3) or caa(3). The nature of the remainingoxidase(s) catalysing oxygen uptake has been studied. Respiratory oxidase activities and the levels of cytochromes b and c increased 2.6- to 4.2-foldon transition from exponential growth, in either of two media, to sporulation stage ill, as previously observed for the parent wild-type strain. NADHoxidase activity at both stages of culture was several-fold higher than ascorbate plus tetramethylp-phenylenediamine (TMPD) oxidase activity, consistent with the TMPD- phenotype of strain PYM1. Oxidase activity with ascorbate as substrate was significant even in the absence of TMPD as electron mediator, suggesting that the terminal oxidase receives electrons from a cytochrome c. Carbon monoxide (CID) difference spectra of membranes were obtainedusing various reductants (ascorbate+/-TMPD, NADH, dithionite) and revealeda haemoprotein resembling cytochrome o'. The CO complex of this cytochromewas photodissociable: the phatodissociation spectrum (photolysed minus CO-ligated) exhibited a trough at 416 nm and a peak at 436 nm, together with minor features in the odp region of the spectrum, consistent with the presence of a cytochrome o'-like pigment. Ca recombination occurred at -85 to -95degrees C, No other haemoproteins showing photoreversible CO binding underthese conditions were detected. Evidence that this pigment was the oxidaseresponsible for substrate oxidation was obtained by photodissociating the CO complex at subzero temperatures in the presence of oxygen; this resultedin faster ligand recombination, attributed to oxygen binding, and extensive oxidation of cytochromes c and b. The oxygen affinity of the oxidase was determined by using the deoxygenation of oxyleghaemoglobin as a sensitive reporter of dissociated oxygen concentration. A single oxidase was revealed with a K-m for oxygen of about 8 nM; this is one of the highest affinities yet reported for a terminal oxidase.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 01/06/20 alle ore 00:15:34