The inner membrane of the mitochondrion folds inwards, forming the cristae. This folding allows a greater amount of membrane to be packed into the mitochondrion. The data in this study demonstrate that subunits e and g of the mitochondrial ATP synthase are involved in generating mitochondrial cristae morphology. These two subunits are non-essential components of ATP synthase and are required for the dimerization and oligomerization of ATP synthase. Mitochondria of yeast cells de®cient in either subunits e or g were found to have numerous digitations and onion-like structures that correspond to an uncontrolled biogenesis and/or folding of the inner mitochondrial membrane. The present data show that there is a link between dimerization of the mitochondrial ATP synthase and cristae morphology. A model is proposed of the assembly of ATP synthase dimers, taking into account the oligomerization of the yeast enzyme and earlier data on the ultrastructure of mitochondrial cristae, which suggests that the association of ATP synthase dimers is involved in the control of the biogenesis of the inner mitochondrial membrane. Keywords: ATP synthase oligomer/mitochondria/ morphology/yeast IntroductionThe mitochondrion is referred to as the`power house' of the cell, because it is responsible for the synthesis of the majority of ATP under aerobic conditions. The inner membrane of the mitochondrion contains the components of the electron transport chain. Oxidation/reduction reactions along the components of the electron transport chain generate a proton gradient that is used by ATP synthase to phosphorylate ADP, thereby producing ATP. To increase the capacity of the mitochondrion to synthesize ATP, the inner membrane is folded to form cristae. These folds allow a much greater amount of electron transport chain enzymes and ATP synthase to be packed into the mitochondrion. However, until now, little was known about how the inner membrane is able to form cristae. This study provides evidence that subunits of ATP synthase are involved in cristae formation.ATP synthase, or F 1 F 0 ATP synthase, is composed of a hydrophilic catalytic unit (F 1 ), which is located in the mitochondrial matrix, and a membranous domain (F 0 ), which anchors the enzyme in the inner mitochondrial membrane and mediates the conduction of protons that participate indirectly in ATP synthesis (Fillingame, 1999;Pedersen et al., 2000). Electron microscopy of negatively stained mitochondria revealed 9 nm diameter projections in the mitochondrial matrix (Ferna Ândez-Mora Ân, 1962), which were identi®ed as the hydrophilic catalytic units (F 1 ) of the F 1 F 0 ATP synthase (Racker et al., 1965). These projections were observed by electron microscopy to be arranged in a non-random, tightly ordered pattern on tubular cristae in Paramecium multimicronucleatum mitochondria using rapid techniques of freezing followed by fracturing, etching and replication (Allen et al., 1989). In this organism, the F 1 complexes are arranged as a double row of particles along the full length ...

Mitochondrial ATP synthase comprises a membrane embedded Fo motor that rotates to drive ATP synthesis in the F1 subunit. We used single-particle cryo-EM to obtain structures of the full complex in a lipid bilayer in the absence or presence of the inhibitor oligomycin, at 3.6 Å and 3.8 Å resolution, respectively. To limit conformational heterogeneity, we locked the rotor in a single conformation by fusing the F6 subunit of the stator with the δ-subunit of the rotor. Assembly of the enzyme with the F6-δ fusion caused a twisting of the rotor and a 9° rotation of the Fo c10-ring in the direction of ATP synthesis, relative to the structure of isolated Fo. Our cryo-EM structures show how F1 and Fo are coupled, give insight into the proton translocation pathway and show how oligomycin blocks ATP synthesis.

We report the high-resolution (1.9 Å) crystal structure of oligomycin bound to the subunit c 10 ring of the yeast mitochondrial ATP synthase. Oligomycin binds to the surface of the c 10 ring making contact with two neighboring molecules at a position that explains the inhibitory effect on ATP synthesis. The carboxyl side chain of Glu59, which is essential for proton translocation, forms an H-bond with oligomycin via a bridging water molecule but is otherwise shielded from the aqueous environment. The remaining contacts between oligomycin and subunit c are primarily hydrophobic. The amino acid residues that form the oligomycin-binding site are 100% conserved between human and yeast but are widely different from those in bacterial homologs, thus explaining the differential sensitivity to oligomycin. Prior genetics studies suggest that the oligomycin-binding site overlaps with the binding site of other antibiotics, including those effective against Mycobacterium tuberculosis, and thereby frames a common "drug-binding site." We anticipate that this drug-binding site will serve as an effective target for new antibiotics developed by rational design. (1). Studies in the 1960s from the laboratory of Efraim Racker demonstrated that the mitochondrial ATP synthase can be separated into two parts, coupling factor 1, or F 1 , which contains the catalytic site for ATP synthesis, and coupling factor o, or F o , which is able to confer sensitivity to oligomycin (2-4). Despite more than 50 y of studies on mitochondrial F 1 F o ATP synthase, the binding site of oligomycin on F o has been elusive. Here we report the oligomycin-binding site on subunit-c of the F o portion of the ATP synthase.Subunit-c of the ATP synthase is an integral membrane protein consisting of two helices, 1 and 2, which span the inner mitochondrial membrane (Fig. 1). Subunit-c assembles as a homomeric ring consisting of 10 subunits in the yeast ATP synthase and eight subunits in the bovine ATP synthase (5, 6). The c-ring forms an essential component of the proton turbine of the ATP synthase, which spins coupled to the movement of protons down a potential gradient. The essential carboxylate of Glu59 in helix 2 of the yeast subunit-c is postulated to participate directly in the movement of protons from the cytosol to the mitochondrial matrix during ATP synthesis. The side-chain carboxyl of Glu59 is nearly in the middle of helix 2, positioning it in the lipid bilayer in the protonated, "closed" conformation (7). Subunit-a is postulated to form two aqueous half-channels that allow protons to gain access to the carboxylate of Glu59 in the "open" conformation, allowing protonation and deprotonation reaction (7).Based on the results presented here, we propose that in the intact ATP synthase, oligomycin binds at the c-ring positioned at the proton channel and blocks proton translocation by blocking access to the essential carboxyl. Furthermore, we propose that the binding site framed out by oligomycin is a common drug-binding site for inhibitors that bind to the ba...

In the past two decades, 7 coronaviruses have infected the human population, with two major outbreaks caused by SARS-CoV and MERS-CoV in the year 2002 and 2012, respectively. Currently, the entire world is facing a pandemic of another coronavirus, SARS-CoV-2, with a high fatality rate. The spike glycoprotein of SARS-CoV-2 mediates entry of virus into the host cell and is one of the most important antigenic determinants, making it a potential candidate for a vaccine. In this study, we have computationally designed a multi-epitope vaccine using spike glycoprotein of SARS-CoV-2. The overall quality of the candidate vaccine was validated in silico and Molecular Dynamics Simulation confirmed the stability of the designed vaccine. Docking studies revealed stable interactions of the vaccine with Toll-Like Receptors and MHC Receptors. The in silico cloning and codon optimization supported the proficient expression of the designed vaccine in E. coli expression system. The efficiency of the candidate vaccine to trigger an effective immune response was assessed by an in silico immune simulation. The computational analyses suggest that the designed multi-epitope vaccine is structurally stable which can induce specific immune responses and thus, can be a potential vaccine candidate against SARS-CoV-2. Wuhan, a city in China, witnessed the outbreak of a febrile respiratory illness on 19th December 2019 due to the coronavirus provisionally named as 2019-nCoV and later SARS-CoV-2 1,2. The disease caused by this coronavirus was named as COVID-19 1,2. Since then, the world is experiencing a grave situation of global public health emergency due to the viral pandemic of severe febrile pneumonia like respiratory syndrome caused by the novel coronavirus 2. Coronaviruses are known to have caused three epidemics in the last two decades, namely COVID-19 in 2019/20, Severe Acute Respiratory Syndrome (SARS) in 2002, and Middle East Respiratory Syndrome (MERS) in 2012 3. As of June 3rd 2020, total cases of SARS-CoV-2 confirmed globally by World Health Organization are 6,287,771 with 379,941 reported deaths (https ://www.who.int/emerg encie s/disea ses/ novel-coron aviru s-2019/situa tion-repor ts). Human coronavirus (H-CoV) is a member of Coronaviridae family, a virus family characterized with the largest RNA genome (26-32 kb), among all of the viruses known till date 4-6. A lipid envelope bilayer containing the spike and membrane proteins surround the positive stranded RNA genome of this virus 7. The spike protein binds to the host cell receptors and releases the viral genome into the host cell, thereby facilitating the viral replication 8. Coronaviruses (CoVs) are mostly associated with respiratory illness and common cold 9 , but can also cause infections in Central Nervous System (CNS) 10. To date, four genera of coronaviruses (α, β, γ, δ) have been identified 11. Human coronaviruses (H-CoVs) belong to α (HCoV-229E and NL63) and β (MERS-CoV, SARS-CoV, HCoV-OC43, HCoV-HKU1 and SARS-CoV-2) genera of coronavirus, respectively 11. In late De...

The crystal structure of yeast mitochondrial F1 ATPase contains three independent copies of the complex, two of which have similar conformations while the third differs in the position of the central stalk relative to the α3β3 sub‐assembly. All three copies display very similar asymmetric features to those observed for the bovine enzyme, but the yeast F1 ATPase structures provide novel information. In particular, the active site that binds ADP in bovine F1 ATPase has an ATP analog bound and therefore this structure does not represent the ADP‐inhibited form. In addition, one of the complexes binds phosphate in the nucleotide‐free catalytic site, and comparison with other structures provides a picture of the movement of the phosphate group during initial binding and subsequent catalysis. The shifts in position of the central stalk between two of the three copies of yeast F1 ATPase and when these structures are compared to those of the bovine enzyme give new insight into the conformational changes that take place during rotational catalysis.