RESUMEN
Cytochrome and lipid composition of membranes is considered as the attributes required for adaptation of the alkalophiles to alkaline conditions. Respiratory chains of alkalophilic representatives of the genus Bacillus are discussed. Special attention is paid to the features of the Na(+)-cycle of these bacteria and to the features determining halo- and alkalotolerant phenotype, which have been reported due to recent achievements in genomics.
Asunto(s)
Bacillus/genética , Bacillus/metabolismo , Metabolismo Energético , Citocromos/metabolismo , Transporte de Electrón , Genómica , Metabolismo de los Lípidos , Modelos Biológicos , Oxidación-Reducción , Fenotipo , Sodio/química , Sodio/metabolismoRESUMEN
We previously identified two oxidases in the membranes of bacterium Bacillus sp. FTU. One of them slowly (caa3) and the other rapidly (bo) recombines with carbon monoxide (CO) after laser flash photolysis, in this respect resembling the Escherichia coli bo- and bd-type oxidases, respectively. In the present study we found three copper atoms in the slowly CO-recombining oxidase from Bacillus sp. FTU. In the other oxidase, the copper content is very low and clearly substoichiometric. Reversed-phase chromatography revealed the presence of haems A and C in the Bacillus sp. FTU copper-containing oxidase and haems B and C in the non-copper-containing one. We thus suggest that the Bacillus sp. FTU oxidase rapidly reacting with CO previously attributed to bo-type by analogy in redox spectrum with the E. coli enzyme be redefined as bb-type oxidase.
Asunto(s)
Bacillus/enzimología , Complejo IV de Transporte de Electrones/metabolismo , Isoenzimas/metabolismo , Monóxido de Carbono/metabolismo , Membrana Celular/enzimología , Cromatografía Líquida de Alta Presión , Cobre/análisis , Complejo IV de Transporte de Electrones/química , Complejo IV de Transporte de Electrones/aislamiento & purificación , Escherichia coli/enzimología , Hemo/análisis , Isoenzimas/química , Isoenzimas/aislamiento & purificación , Rayos Láser , Fotólisis , EspectrofotometríaRESUMEN
The kinetics of CO rebinding with isolated Bacillus FTU caa3-type oxidase and with solubilized Escherichia coli membranes (GO103 strain) containing the o-type oxidase as the main O2-reducing enzyme were studied under reducing conditions by laser flash photolysis of the CO-oxidase complexes. The spectra of the optical absorbance changes upon photolysis were characteristic of CO-caa3- and CO-o-oxidase complexes in Bac. FTU and E. coli, respectively. Small quantities of d-type oxidase in E. coli GO103 membranes were detected. The kinetics of CO reassociation with reduced caa3- and o-type oxidases were monophasic with tau 25-30 ms in both cases.