Reconstitution, spectroscopy, and redox properties of the photosynthetic recombinant cytochrome b 559 from higher plants
|Author||Luján Serrano, María Ángeles
Martínez, Jesús I.
Alonso, Pablo J.
Guerrero Rodríguez, Fernando
Roncel Gil, Mercedes
Ortega Rodríguez, José María
Yruela Guerrero, Inmaculada
Picorel Castaño, Rafael
|Department||Universidad de Sevilla. Departamento de Bioquímica Vegetal y Biología Molecular|
|Abstract||A study of the in vitro reconstitution of sugar beet cytochrome b 559 of the photosystem II is described. Both α and β cytochrome subunits were first cloned and expressed in Escherichia coli. In vitro reconstitution of ...
A study of the in vitro reconstitution of sugar beet cytochrome b 559 of the photosystem II is described. Both α and β cytochrome subunits were first cloned and expressed in Escherichia coli. In vitro reconstitution of this cytochrome was carried out with partially purified recombinant subunits from inclusion bodies. Reconstitution with commercial heme of both (αα) and (ββ) homodimers and (αβ) heterodimer was possible, the latter being more efficient. The absorption spectra of these reconstituted samples were similar to that of the native heterodimer cytochrome b 559 form. As shown by electron paramagnetic resonance and potentiometry, most of the reconstituted cytochrome corresponded to a low spin form with a midpoint redox potential +36 mV, similar to that from the native purified cytochrome b 559. Furthermore, during the expression of sugar beet and Synechocystis sp. PCC 6803 cytochrome b 559 subunits, part of the protein subunits were incorporated into the host bacterial inner membrane, but only in the case of the β subunit from the cyanobacterium the formation of a cytochrome b 559-like structure with the bacterial endogenous heme was observed. The reason for that surprising result is unknown. This in vivo formed (ββ) homodimer cytochrome b 559-like structure showed similar absorption and electron paramagnetic resonance spectral properties as the native purified cytochrome b 559. A higher midpoint redox potential (+126 mV) was detected in the in vivo formed protein compared to the in vitro reconstituted form, most likely due to a more hydrophobic environment imposed by the lipid membrane surrounding the heme.
|Citation||Luján Serrano, M.Á., Martínez, J.I., Alonso, P.J., Guerrero Rodríguez, F., Roncel Gil, M., Ortega Rodríguez, J.M.,...,Picorel Castaño, R. (2012). Reconstitution, spectroscopy, and redox properties of the photosynthetic recombinant cytochrome b 559 from higher plants. Photosynthesis Research, 112 (3), 193-204.|