The work of the VB Borisov research group is devoted to investigation of a mechanism of energy transformation in bacteria on the molecular level. Of particular interest is the structure and the mechanism of function of a bd-type terminal oxidase.
The bd-type terminal oxidase is an energy-transducing respiratory enzyme both in the microorganisms harmless for humans and animals, and in bacteria causing various diseases, such as dysentery, pneumonia, salmonellosis, periodontitis, brucellosis, typhoid, tuberculosis. A positive correlation between virulence of bacterial pathogens responsible for these diseases and a level of cytochrome bd expression was reported. The cytochrome bd contents grow up under unfavorable conditions, such as lower oxygen concentration, the presence of poisons in the environment (for example, cyanide), uncouplers-protonophores, sharp change in ambient temperature and in a number of other cases when the traditional terminal oxidases are not capable to function, whereas the “alternative” cytochrome bd successfully works. In nitrogen-fixing bacteria, cytochrome bd takes part in respiratory protection of nitrogenase against oxygen. Cytochrome bd from E. coli is involved in regulation of the disulfide bond formation upon protein folding in a cell. Our data on unusually high NO dissociation from the cytochrome bd active site (in comparison with that of cytochrome c oxidase and other heme-copper oxidases) throw light on how a bd-type enzyme can help a pathogenic enterobacterium to overcome immune protection of the host cell.
The enzyme consists of the two subunits, each one being a typical integral membrane protein. These subunits carry the three redox-centers: one low-spin (heme b558) and two high-spin (hemes b595 and d). Heme b558 apparently takes part in the oxidation of ubiquinol. Heme d binds oxygen and likely takes part in the oxygen-reducing reaction. The role of heme b595 remains to be obscure.
The structure and properties of the main intermediates of the catalytic cycle of the bd enzymes have been determined. The existence of excitonic interactions between hemes b595 and d has been detected. A model of arrangement and operation of the active site of the bd-type terminal oxidases, scheme for the reaction of cytochrome bd with oxygen, and a model of intraprotein pathways of electrons and protons in these enzymes have been suggested.
State Prize Award for young scientists [the highest scientific award in Russia] (1999)
Award of the Biochemical Society of Russia for young scientists (2000)
Award for young scientists for the best research in Belozersky Institute (2000)
Award of the Russian Higher Education Academy of Sciences for young scientists (2000)
Award for young scientists for the best research in Moscow State University (2001)
Academia Europaea Prize for Young Russian Scientists (2002)
Shuvalov Award of Moscow State University (2007)
The work is supported by Russian Foundation for Basic Research (RFBR). We collaborate with University of Rome and CNR Institute of Molecular Biology and Pathology (Italy), University of Helsinki (Finland), University of Illinois at Urbana-Shampaign (USA), University of Tokyo and Kyushu Institute of Technology (Japan), Ecole Polytechnique at Palaiseau and Institut de Biologie Physico-Chimique at Paris (France), University of Sheffield (England).