A new twist of rubredoxin function in M. tuberculosis.

Affiliation

Sushko T(1), Kavaleuski A(2), Grabovec I(2), Kavaleuskaya A(2), Vakhrameev D(3), Bukhdruker S(4), Marin E(3), Kuzikov A(5), Masamrekh R(5), Shumyantseva V(5), Tsumoto K(6), Borshchevskiy V(7), Gilep A(8), Strushkevich N(9).
Author information:
(1)The Institute of Medical Science, the University of Tokyo, Tokyo, Japan.
(2)Institute of Bioorganic Chemistry, National Academy of Sciences of Belarus, Minsk, Belarus.
(3)Research Center for Molecular Mechanisms of Aging and Age-Related Diseases, Moscow, Institute of Physics and Technology
(MIPT), Dolgoprudny, Russia.
(4)Research Center for Molecular Mechanisms of Aging and Age-Related Diseases, Moscow, Institute of Physics and Technology
(MIPT), Dolgoprudny, Russia; Institute of Biological Information Processing
(IBI-7: Structural Biochemistry), Forschungszentrum Jülich GmbH, 52425 Jülich, Germany; JuStruct: Jülich Center for Structural Biology, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany; ESRF - The European Synchrotron, 38000 Grenoble, France.
(5)Institute of Biomedical Chemistry, Moscow, Russia; Pirogov Russian National Research Medical University, Moscow, Russia.
(6)The Institute of Medical Science, the University of Tokyo, Tokyo, Japan; Department of Bioengineering, School of Engineering, the University of Tokyo, Tokyo, Japan.
(7)Research Center for Molecular Mechanisms of Aging and Age-Related Diseases, Moscow, Institute of Physics and Technology
(MIPT), Dolgoprudny, Russia; Institute of Biological Information Processing
(IBI-7: Structural Biochemistry), Forschungszentrum Jülich GmbH, 52425 Jülich, Germany; JuStruct: Jülich Center for Structural Biology, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
(8)Institute of Bioorganic Chemistry, National Academy of Sciences of Belarus, Minsk, Belarus; Institute of Biomedical Chemistry, Moscow, Russia.
(9)Skolkovo Institute of Science and Technology, Moscow, Russia. Electronic address: [Email]

Abstract

Electron transfer mediated by metalloproteins drives many biological processes. Rubredoxins are a ubiquitous [1Fe-0S] class of electron carriers that play an important role in bacterial adaptation to changing environmental conditions. In Mycobacterium tuberculosis, oxidative and acidic stresses as well as iron starvation induce rubredoxins expression. However, their functions during M. tuberculosis infection are unknown. In the present work, we show that rubredoxin B (RubB) is able to efficiently shuttle electrons from cognate reductases, FprA and FdR to support catalytic activity of cytochrome P450s, CYP124, CYP125, and CYP142, which are important for bacterial viability and pathogenicity. We solved the crystal structure of RubB and characterized the interaction between RubB and CYPs using site-directed mutagenesis. Mutations that not only neutralize single charge but also change the specific residues on the surface of RubB did not dramatically decrease activity of studied CYPs. Together with isothermal calorimetry (ITC) experiments, the obtained results suggest that interactions are transient and not highly specific. The redox potential of RubB is -264 mV vs. Ag/AgCl and the measured extinction coefficients are 9931 M-1cm-1 and 8371 M-1cm-1 at 380 nm and 490 nm, respectively. Characteristic parameters of RubB along with the discovered function might be useful for biotechnological applications. Our findings suggest that a switch from ferredoxins to rubredoxins might be crucial for M. tuberculosis to support CYPs activity during the infection.