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Spectral and redox properties of a mouse cytochrome b561 protein suggest transmembrane electron transfer function

Aug 31 - csütörtök

09:50 – 10:10

Bioenergetika és fotobiofizika

E38

Spectral and redox properties of a mouse cytochrome b561 protein suggest transmembrane electron transfer function

Alajos Bérczi1, Zsuzsanna Márton1, Krisztina Laskay1, András Tóth1,2, Gábor Rákhely1,2, Ágnes Duzs1,2, Krisztina Sebők-Nagy1, Tibor Páli1 and László Zimányi1

1 Biological Research Centre, Szeged, Institute of Biophysics

2 University of Szeged, Faculty of Science and Informatics, Department of Biotechnology

Cytochrome b561 proteins (CYB561s) are integral membrane proteins with 6 trans membrane domains, two heme b redox centers, one on each side of the host membrane. The major characteristics of these proteins are their ascorbate reducibility and transmembrane electron transferring capability. More than one CYB561 can be found in a wide range of animal and plant phyla and they are localized in membranes different from the membranes participating in bioenergization. Two homologous proteins, both in humans and rodents, are thought to participate via yet unidentified way in cancer pathology. The recombinant forms of the human tumor suppressor 101F6 protein (Hs_CYB561D2 and its mouse ortholog (Mm_CYB561D2 have already been studied in some details. However, nothing has yet been published about the physical- chemical properties of their homologues (Hs_CYB561D1 in humans and Mm_CYB561D1 in mice). The tissue specificity, location and function of this protein is unknown. Here we present optical, redox and structural properties of the recombinant Mm_CYB561D1 obtained based on various spectroscopic methods and homology modeling. In a new model calculation we show that traditional evaluation of the redox titration of these proteins cannot unequivocally provide the midpoint redox potentials of the individual heme centers without further assumptions. The interaction with ascorbate, the redox properties, the (limited) sequence homology and the modelled 3D structure all substantiate the function of Mm_CYB561D1 as a transmembrane electron transporter with ascorbate as the primary electron donor [1].

References

[1] Bérczi A, Márton Z, Laskay K, Tóth A, Rákhely G, Duzs Á, Sebők-Nagy K, Páli T, Zimányi L (2023)

Molecules 28: 2261.