Skulachev 2015 Abstract MiP2015
|Moscow news: two more representatives of sodium motive force generators (Na+-cbb3 oxidase and Na+-bacteriorhodopsin); natural delay of the aging program (neoteny) in mammals, namely in naked mole rat and “naked ape” (human).|
Skulachev VP (2015)
M.S. Muntyan and coworkers  in our group succeeded in describing Na+ - motive terminal oxidase from the extremely alkalophilic bacterium Thioalkalivibrio versutus living in alkaline Siberian soda lakes at saturating salt concentration. At such conditions, this respiring bacterium cannot employ Mitchellian H+ cycle because two constituents of proton motive force, ∆ψ and ∆pH, are oppositely directed. It was found that (i) respiration and ∆ψ in Th. vesutus show pH optimum at pH 9, (ii) both respiration and ∆ψ at this pH are stimulated by Na+, whereas K+, Li+ and choline+ are ineffective, (iii) respiration is coupled to extrusion of Na+ from the cell or right-side out vesicles, the extrusion being stimulated by protonophorous uncouplers, (iv) Paracoccus denitrificans mutant lacking all terminal oxidases and displaying no respiration-driven Na+ pumping became capable of such a pumping after expression of Th. versutus cbb3. The above listed data directly demonstrated for the first time the existence of a terminal oxidase pumping Na+ instead of H+.
In 2013-2015, a Na+ - pumping bacteriorhodopsin was described in several marine flavobacteria . In our group, Bogachev and coworkers expressed Na+ - bacteriorhodopsin (NaR) from Dokdonia sp. PRO95 in E. coli . It was found that such E. coli cells show light-dependent Na+ pumping which is stimulated by protonophores. E.coli-expressed NaR was incorporated into proteoliposomes that were attached to phospholipid – impregrated collodion film. Illumination of such a film by a single 15 ns laser flash resulted in generation of ∆ψ up to 200 mV, directly measured by two electrodes separated by the film. The following four steps were identified in the NaR photocycle: NaR519 + hν → K595 → (L450 ↔ M495) → O585 → NaR519. The first step was too fast to be separated from the second one. Contributions of steps (2), (3) and (4) to the total ∆ψ proved to be 15, 15 and 70 %, respectively. Step (3) was the only one which was Na+ dependent. Li+, but not K+, substituted for Na+. An interesting possibility consists in that NaR evolutionary was a primary energy generator in biosphere.
• O2k-Network Lab: RU Moscow Skulachev VP
Labels: MiParea: Respiration, nDNA;cell genetics, Comparative MiP;environmental MiP Pathology: Aging;senescence Stress:Cell death, Oxidative stress;RONS Organism: Human, Other mammals, Eubacteria Tissue;cell: Heart, Nervous system
Event: D1 MiP2015
Belozersky Inst Physico-Chemical Biol, Lomonosov Moscow State Univ, Moscow, Russia. - [email protected]
For several years, our group has been studying the role of mitochondria and mitochondrial reactive oxygen species (mROS) in aging program of mammals. Naked mole rat represents the most interesting model to study aging of mammals. This rodent is as small as a mouse but lives at least 10 times longer. For a naked mole rat, cancer, cardiovascular and brain pathologies, diabetes, infections and other aging-stimulated diseases are absent from the list of reasons of death, mortality is very low and age-independent, fertility seems to not decrease with age. E. Rüppell, who discovered naked mole rats, stressed that its adult form resembles in some aspects newborn rodents of the same Bathyergidae family, being much smaller and having, like newborn rodents, no fur, auricles and scroptum. Later some other features typical to newborn mammals were also revealed, i.e. inability to maintain stable body temperature below thermoneutrality, underdevelopment of vomeronasal organ, low expression of insulin and IGF1 and high expression of IGF2 genes. FAS – activated proinflammatory serine/threonine kinase (FASTK) is absent from naked mole rat. This suggests that “inflammoaging” is suppressed in these animals. mROS seem to play a key role in aging: O2 → mROS → H2O2 → apoptosis, necrosis → decrease in cellularity of organs → decay of functions. It was found that extracellular concentration of potent antioxidant hyaluronan is very high in naked mole rat cell cultures, which explains (a) why added H2O2 fails to induce apoptosis of these cultures and (b) very high resistance of hippocampal neurons of naked mole rat to anoxia / reoxygenation. Experiments performed by our group in cooperation with the group of Th. Hildebrandt (Berlin) showed that heart mitochondria from naked mole rat (i) contain lower concentration of adenine nucleotides and (ii) respire much faster after exhaustion of added ADP than before ADP addition. The effect (ii) might be regarded as a mechanism lowering mROS generation. Both, effect (i) and (ii), are inherent in mitochondria from embryo and neonatal rodents . In general, longevity of naked mole rats can be considered as the precedent of neoteny, i.e. extension of youth and delay of aging, a phenomenon known in amphibian (the axolotl / salamander case).
Neotenic aspect of human ontogenesis was investigated since 1926 when L. Bolk suggested that this process differ from ape ontogenesis by extension of childhood and youth. The main argument in favor of such a possibility consisted in that ape embryos and young apes resemble humans much more than apes. In other words, apes are brutalized from a human-like child when they are transformed from young to adult. The following neotenic traits were found to be inherent in the adult humans and young apes but not in adult apes: relatively large skull, thin skull bones, small fangs, flattered and broadened face, ear shape, small nose, hairless body, absence of baculum, short limbs compared to torso, longer legs compared to arms, smaller mass of skeletal muscles. An important discovery was recently made by Ph. Khaitovich and coworkers. The authors showed that initiation of transcription of a large group of genes encoding proteins of prefrontal brain cortex in prenatal and early postnatal periods occurs much later in humans than in chimpanzee and rhesus macaques. Among these genes, there are those encoding synaptic proteins. Nevertheless, the size of the adult brain is larger in humans than in apes. Finally, humans become much more developed in cognitive aspects but underdeveloped in such aspects as physical (muscular) force. In particular, construction of some parts of skeleton (e.g. feet) is clearly more primitive in humans than in apes, as if the common ancestor of humans and apes was more human-like than ape-like. Curves of mortality vs. age for humans start at extremely low mortality in youth (it is much lower than for young apes). However, in elderly, the human mortality values eventually become higher than for apes. An impression arises that in humans a mechanism controlling results of operation of aging program stimulates this program in the end of our life.
In conclusion, extension of youth by delay of aging is impossible to imagine within the framework of the concept of stochastic (non-programmed) aging but can be explained if aging is programed .
- Muntyan MS, Cherepanov DA, Malinen AM, Bloch DA, Sorokin DY, Severina II, Ivashina TV, Lahti R, Muyzer G, Skulachev VP (2015) Cytochrome cbb3 of Thioalkalivibrio is a Na+-pumping cytochrome oxidase. PNAS 112:7695-700.
- Inoue K, Ono H, Abe-Yoshizumi R, Yoshizawa S, Ito H, Kogure K, Kandori H (2013) A light-driven sodium ion pump in marine bacteria. Nat. Commun., 4:1678.
- Bertsova YV, Bogachev AV, Skulachev VP (2015) Proteorhodopsin from Dokdonia sp. PRO95 is a light-driven Na+-pump. Biochemistry(Mosc) 80:449-54.
- Bogachev AA, Bertsova YV, Verkhovskaya ML, Mamedov MD, Skulachev VP (2015) Real-time kinetics of electrogenic transport of sodium ions by proteorhodopsin. Plos Biol (submitted).
- Skulachev VP, Vyssokikh MY, Skulachev MV, Holtze S, Platzer M, Morhart M, Hildebrandt TB (2015) Neoteny, physiological phenomenon of delay of aging program: from naked mole rat to “naked ape” (human). Physiol Rev (in press).