An HSP90 cochaperone Ids2 maintains the stability of mitochondrial DNA and ATP synthase

Abstract Background Proteostasis unbalance and mitochondrial dysfunction are two hallmarks of aging. While the chaperone folds and activates its clients, it is the cochaperone that determines the specificity of the clients. Ids2 is an HSP90’s cochaperone controlling mitochondrial functions, but no in vivo clients of Ids2 have been reported yet. Results We performed a screen of the databases of HSP90 physical interactors, mitochondrial components, and mutants with respiratory defect, and identified Atp3, a subunit of the complex V ATP synthase, as a client of Ids2. Deletion of IDS2 destabilizes Atp3, and an α-helix at the middle region of Ids2 recruits Atp3 to the folding system. Shortage of Ids2 or Atp3 leads to the loss of mitochondrial DNA. The intermembrane space protease Yme1 is critical to maintaining the Atp3 protein level. Moreover, Ids2 is highly induced when cells carry out oxidative respiration. Conclusions These findings discover a cochaperone essentially for maintaining the stability of mitochondrial DNA and the proteostasis of the electron transport chain—crosstalk between two hallmarks of aging.

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Extrinsic conditions influence the self-association and structure of IF1, the regulatory protein of mitochondrial ATP synthase

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1903535116 ◽

2019 ◽

Vol 116 (21) ◽

pp. 10354-10359 ◽

Cited By ~ 7

Author(s):

Vytaute Boreikaite ◽

Basile I. M. Wicky ◽

Ian N. Watt ◽

Jane Clarke ◽

John E. Walker

Keyword(s):

Atp Synthase ◽

Atp Hydrolysis ◽

Regulatory Protein ◽

Coiled Coil ◽

The Self ◽

Intrinsically Disordered ◽

Mitochondrial Atp Synthase ◽

Self Association ◽

Α Helix

The endogenous inhibitor of ATP synthase in mitochondria, called IF1, conserves cellular energy when the proton-motive force collapses by inhibiting ATP hydrolysis. Around neutrality, the 84-amino-acid bovine IF1 is thought to self-assemble into active dimers and, under alkaline conditions, into inactive tetramers and higher oligomers. Dimerization is mediated by formation of an antiparallel α-helical coiled-coil involving residues 44–84. The inhibitory region of each monomer from residues 1–46 is largely α-helical in crystals, but disordered in solution. The formation of the inhibited enzyme complex requires the hydrolysis of two ATP molecules, and in the complex the disordered region from residues 8–13 is extended and is followed by an α-helix from residues 14–18 and a longer α-helix from residue 21, which continues unbroken into the coiled-coil region. From residues 21–46, the long α-helix binds to other α-helices in the C-terminal region of predominantly one of the β-subunits in the most closed of the three catalytic interfaces. The definition of the factors that influence the self-association of IF1 is a key to understanding the regulation of its inhibitory properties. Therefore, we investigated the influence of pH and salt-types on the self-association of bovine IF1 and the folding of its unfolded region. We identified the equilibrium between dimers and tetramers as a potential central factor in the in vivo modulation of the inhibitory activity and suggest that the intrinsically disordered region makes its inhibitory potency exquisitely sensitive and responsive to physiological changes that influence the capability of mitochondria to make ATP.

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Regulation of COX Assembly and Function by Twin CX9C Proteins—Implications for Human Disease

Cells ◽

10.3390/cells10020197 ◽

2021 ◽

Vol 10 (2) ◽

pp. 197

Author(s):

Stephanie Gladyck ◽

Siddhesh Aras ◽

Maik Hüttemann ◽

Lawrence I. Grossman

Keyword(s):

Electron Transport ◽

Cytochrome C ◽

Atp Synthase ◽

Protein Interactions ◽

Human Disease ◽

Electron Transport Chain ◽

Intermembrane Space ◽

Protein Protein Interactions ◽

Inner Mitochondrial Membrane ◽

Transport Chain

Oxidative phosphorylation is a tightly regulated process in mammals that takes place in and across the inner mitochondrial membrane and consists of the electron transport chain and ATP synthase. Complex IV, or cytochrome c oxidase (COX), is the terminal enzyme of the electron transport chain, responsible for accepting electrons from cytochrome c, pumping protons to contribute to the gradient utilized by ATP synthase to produce ATP, and reducing oxygen to water. As such, COX is tightly regulated through numerous mechanisms including protein–protein interactions. The twin CX9C family of proteins has recently been shown to be involved in COX regulation by assisting with complex assembly, biogenesis, and activity. The twin CX9C motif allows for the import of these proteins into the intermembrane space of the mitochondria using the redox import machinery of Mia40/CHCHD4. Studies have shown that knockdown of the proteins discussed in this review results in decreased or completely deficient aerobic respiration in experimental models ranging from yeast to human cells, as the proteins are conserved across species. This article highlights and discusses the importance of COX regulation by twin CX9C proteins in the mitochondria via COX assembly and control of its activity through protein–protein interactions, which is further modulated by cell signaling pathways. Interestingly, select members of the CX9C protein family, including MNRR1 and CHCHD10, show a novel feature in that they not only localize to the mitochondria but also to the nucleus, where they mediate oxygen- and stress-induced transcriptional regulation, opening a new view of mitochondrial-nuclear crosstalk and its involvement in human disease.

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An HSP90 Cochaperone Ids2 Maintains the Stability of Mitochondrial DNA and ATP Synthase

SSRN Electronic Journal ◽

10.2139/ssrn.3803608 ◽

2021 ◽

Author(s):

Pei-Heng Jiang ◽

Chen-Yan Hou ◽

Shu-Chun Teng

Keyword(s):

Mitochondrial Dna ◽

Atp Synthase ◽

The Stability

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Functional analysis of membranous Fo-a subunit of F1Fo-ATP synthase by in vitro protein synthesis

Biochemical Journal ◽

10.1042/bj20111284 ◽

2012 ◽

Vol 442 (3) ◽

pp. 631-638 ◽

Cited By ~ 38

Author(s):

Yutetsu Kuruma ◽

Toshiharu Suzuki ◽

Sakurako Ono ◽

Masasuke Yoshida ◽

Takuya Ueda

Keyword(s):

Protein Synthesis ◽

Atp Synthase ◽

Transmembrane Helix ◽

Atp Synthesis ◽

Membrane Vesicles ◽

F1fo Atp Synthase ◽

Pure System ◽

A Subunit

The a subunit of F1Fo (F1Fo-ATP synthase) is a highly hydrophobic protein with five putative transmembrane helices which plays a central role in H+-translocation coupled with ATP synthesis/hydrolysis. In the present paper, we show that the a subunit produced by the in vitro protease-free protein synthesis system (the PURE system) is integrated into a preformed Foa-less F1Fo complex in Escherichia coli membrane vesicles and liposomes. The resulting F1Fo has a H+-coupled ATP synthesis/hydrolysis activity that is approximately half that of the native F1Fo. By using this procedure, we analysed five mutations of F1Fo, where the conserved residues in the a subunit (Asn90, Asp112, Arg169, Asn173 and Gln217) were individually replaced with alanine. All of the mutant Foa subunits were successfully incorporated into F1Fo, showing the advantage over conventional expression in E. coli by which three (N90A, D112A, and Q217A) mutant a subunits were not found in F1Fo. The N173A mutant retained full activity and the mutants D112A and Q217A had weak, but detectable, activity. No activity was observed for the R169A and N90A mutants. Asn90 is located in the middle of putative second transmembrane helix and likely to play an important role in H+-translocation. The present study exemplifies that the PURE system provides an alternative approach when in vivo expression of membranous components in protein complexes turns out to be difficult.

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Structure of ATP synthase from Paracoccus denitrificans determined by X-ray crystallography at 4.0 Å resolution

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1517542112 ◽

2015 ◽

Vol 112 (43) ◽

pp. 13231-13236 ◽

Cited By ~ 89

Author(s):

Edgar Morales-Rios ◽

Martin G. Montgomery ◽

Andrew G. W. Leslie ◽

John E. Walker

Keyword(s):

Atp Synthase ◽

Paracoccus Denitrificans ◽

Release Site ◽

Membrane Domain ◽

X Ray ◽

X Ray Crystallography ◽

Central Stalk ◽

C Subunit ◽

A Subunit ◽

Α Helix

The structure of the intact ATP synthase from the α-proteobacterium Paracoccus denitrificans, inhibited by its natural regulatory ζ-protein, has been solved by X-ray crystallography at 4.0 Å resolution. The ζ-protein is bound via its N-terminal α-helix in a catalytic interface in the F1 domain. The bacterial F1 domain is attached to the membrane domain by peripheral and central stalks. The δ-subunit component of the peripheral stalk binds to the N-terminal regions of two α-subunits. The stalk extends via two parallel long α-helices, one in each of the related b and b′ subunits, down a noncatalytic interface of the F1 domain and interacts in an unspecified way with the a-subunit in the membrane domain. The a-subunit lies close to a ring of 12 c-subunits attached to the central stalk in the F1 domain, and, together, the central stalk and c-ring form the enzyme’s rotor. Rotation is driven by the transmembrane proton-motive force, by a mechanism where protons pass through the interface between the a-subunit and c-ring via two half-channels in the a-subunit. These half-channels are probably located in a bundle of four α-helices in the a-subunit that are tilted at ∼30° to the plane of the membrane. Conserved polar residues in the two α-helices closest to the c-ring probably line the proton inlet path to an essential carboxyl group in the c-subunit in the proton uptake site and a proton exit path from the proton release site. The structure has provided deep insights into the workings of this extraordinary molecular machine.

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Formation and Structure of Casein Micelles in Lactating Mammary Tissue

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100067741 ◽

1970 ◽

Vol 28 ◽

pp. 150-151

Author(s):

Robert J. Carroll ◽

Marvin P. Thompson ◽

Harold M. Farrell

Keyword(s):

Size Distribution ◽

G Protein ◽

Milk Proteins ◽

Mammary Tissue ◽

Colloidal System ◽

Casein Micelles ◽

The Stability

Milk is an unusually stable colloidal system; the stability of this system is due primarily to the formation of micelles by the major milk proteins, the caseins. Numerous models for the structure of casein micelles have been proposed; these models have been formulated on the basis of in vitro studies. Synthetic casein micelles (i.e., those formed by mixing the purified αsl- and k-caseins with Ca2+ in appropriate ratios) are dissimilar to those from freshly-drawn milks in (i) size distribution, (ii) ratio of Ca/P, and (iii) solvation (g. water/g. protein). Evidently, in vivo organization of the caseins into the micellar form occurs in-a manner which is not identical to the in vitro mode of formation.

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Kinetics of Various 99mTc-Sn-Pyrophosphate Compounds in the Rat

Nuklearmedizin ◽

10.1055/s-0037-1620623 ◽

1977 ◽

Vol 16 (04) ◽

pp. 157-162 ◽

Cited By ~ 1

Author(s):

C. Schümichen ◽

B. Mackenbrock ◽

G. Hoffmann

Keyword(s):

Normal Saline ◽

Half Life ◽

Compound A ◽

Short Half Life ◽

Low Concentrations ◽

The Stability ◽

Kinetics Of ◽

In Vitro Stability

SummaryThe bone-seeking 99mTc-Sn-pyrophosphate compound (compound A) was diluted both in vitro and in vivo and proved to be unstable both in vitro and in vivo. However, stability was much better in vivo than in vitro and thus the in vitro stability of compound A after dilution in various mediums could be followed up by a consecutive evaluation of the in vivo distribution in the rat. After dilution in neutral normal saline compound A is metastable and after a short half-life it is transformed into the other 99mTc-Sn-pyrophosphate compound A is metastable and after a short half-life in bone but in the kidneys. After dilution in normal saline of low pH and in buffering solutions the stability of compound A is increased. In human plasma compound A is relatively stable but not in plasma water. When compound B is formed in a buffering solution, uptake in the kidneys and excretion in urine is lowered and blood concentration increased.It is assumed that the association of protons to compound A will increase its stability at low concentrations while that to compound B will lead to a strong protein bond in plasma. It is concluded that compound A will not be stable in vivo because of a lack of stability in the extravascular space, and that the protein bond in plasma will be a measure of its in vivo stability.

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Applicability of Instability Index for In vitro Protein Stability Prediction

Protein and Peptide Letters ◽

10.2174/0929866526666190228144219 ◽

2019 ◽

Vol 26 (5) ◽

pp. 339-347 ◽

Cited By ~ 4

Author(s):

Dilani G. Gamage ◽

Ajith Gunaratne ◽

Gopal R. Periyannan ◽

Timothy G. Russell

Keyword(s):

Protein Stability ◽

Caulobacter Crescentus ◽

Effect Of Temperature ◽

Instability Index ◽

Dipeptide Composition ◽

Experimental Conditions ◽

The Stability ◽

Vitro Protein

Background: The dipeptide composition-based Instability Index (II) is one of the protein primary structure-dependent methods available for in vivo protein stability predictions. As per this method, proteins with II value below 40 are stable proteins. Intracellular protein stability principles guided the original development of the II method. However, the use of the II method for in vitro protein stability predictions raises questions about the validity of applying the II method under experimental conditions that are different from the in vivo setting. Objective: The aim of this study is to experimentally test the validity of the use of II as an in vitro protein stability predictor. Methods: A representative protein CCM (CCM - Caulobacter crescentus metalloprotein) that rapidly degrades under in vitro conditions was used to probe the dipeptide sequence-dependent degradation properties of CCM by generating CCM mutants to represent stable and unstable II values. A comparative degradation analysis was carried out under in vitro conditions using wildtype CCM, CCM mutants and two other candidate proteins: metallo-β-lactamase L1 and α -S1- casein representing stable, borderline stable/unstable, and unstable proteins as per the II predictions. The effect of temperature and a protein stabilizing agent on CCM degradation was also tested. Results: Data support the dipeptide composition-dependent protein stability/instability in wt-CCM and mutants as predicted by the II method under in vitro conditions. However, the II failed to accurately represent the stability of other tested proteins. Data indicate the influence of protein environmental factors on the autoproteolysis of proteins. Conclusion: Broader application of the II method for the prediction of protein stability under in vitro conditions is questionable as the stability of the protein may be dependent not only on the intrinsic nature of the protein but also on the conditions of the protein milieu.

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Stability and ocular biodistribution of topically administered PLGA nanoparticles

Scientific Reports ◽

10.1038/s41598-021-90792-5 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Sean Swetledge ◽

Renee Carter ◽

Rhett Stout ◽

Carlos E. Astete ◽

Jangwook P. Jung ◽

...

Keyword(s):

Uv Light ◽

Light Exposure ◽

Polymeric Nanoparticles ◽

Plga Nanoparticles ◽

Eye Disease ◽

Control Group ◽

Eye Tissues ◽

Nanoparticle Morphology ◽

The Stability

AbstractPolymeric nanoparticles have been investigated as potential delivery systems for therapeutic compounds to address many ailments including eye disease. The stability and spatiotemporal distribution of polymeric nanoparticles in the eye are important regarding the practical applicability and efficacy of the delivery system in treating eye disease. We selected poly(lactic-co-glycolic acid) (PLGA) nanoparticles loaded with lutein, a carotenoid antioxidant associated with eye health, as our model ophthalmic nanodelivery system and evaluated its stability when suspended in various conditions involving temperature and light exposure. We also assessed the ocular biodistribution of the fluorescently labeled nanoparticle vehicle when administered topically. Lutein-loaded nanoparticles were stable in suspension when stored at 4 °C with only 26% lutein release and no significant lutein decay or changes in nanoparticle morphology. When stored at 25 °C and 37 °C, these NPs showed signs of bulk degradation, had significant lutein decay compared to 4 °C, and released over 40% lutein after 5 weeks in suspension. Lutein-loaded nanoparticles were also more resistant to photodegradation compared to free lutein when exposed to ultraviolet (UV) light, decaying approximately 5 times slower. When applied topically in vivo, Cy5-labled nanoparticles showed high uptake in exterior eye tissues including the cornea, episcleral tissue, and sclera. The choroid was the only inner eye tissue that was significantly higher than the control group. Decreased fluorescence in all exterior eye tissues and the choroid at 1 h compared to 30 min indicated rapid elimination of nanoparticles from the eye.

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