Synthesis of the inner mitochondrial membrane and the intercalation of respiratory enzymes during the cell cycle of Chlorella

1976 ◽  
Vol 21 (2) ◽  
pp. 329-340
Author(s):  
B.G. Forde ◽  
B.E. Gunning ◽  
P.C. John
Keyword(s):  
Cell Cycle ◽  
Succinate Dehydrogenase ◽  
Mitochondrial Membrane ◽  
Extended Period ◽  
Outer Mitochondrial Membrane ◽  
Inner Mitochondrial Membrane ◽  
Chlorella Fusca ◽  
Respiratory Enzymes ◽  
Membrane Area ◽  
Enzyme Molecules

The ratio of inner to outer mitochondrial membrane area remains close to 1–8 throughout the cell cycle in synchronized cells of Chlorella fusca var, vacuolata 211-8p. Using estimates of this ratio, together with our previous estimates of mitochondrial surface area, to calculate the absolute area of inner mitochondrial membrane, it is demonstrated that growth of the inner mitochondrial membrane during the cell cycle occupies an extended period and parallels the growth of the whole cell. In contrast, the synthesis of succinate dehydrogenase and cytochrome oxidase is restricted to the last third of the cell cycle. It is concluded that mitochondrial growth involves the intercalation of periodically synthesized respiratory enzymes into membranes made earlier in the cycle, with consequent 5-fold changes in the density of active enzyme molecules in the membrane. These observations are discussed in relation to the control of mitochondiral membrane synthesis, membrane assembly and respiration rate during the cell cycle.

Relationships between mitochondrial outer membranes and agranular reticulum in nervous tissue: ultrastructural observations and a new interpretation

1980 ◽  
Vol 46 (1) ◽  
pp. 129-147
Author(s):  
J. Spacek ◽  
A.R. Lieberman
Keyword(s):  
Nervous Tissue ◽  
Mitochondrial Membrane ◽  
Nerve Cells ◽  
Outer Mitochondrial Membrane ◽  
Inner Mitochondrial Membrane ◽  
Thin Sections ◽  
3 Dimensional ◽  
Outer Membranes ◽  
New Interpretation ◽  
In Cells

This study is concerned with extensions of the outer membranes of mitochondria in cells of nervous tissue, and with possible relationships between the extensions and the agranular reticulum. A variety of preparative techniques was applied to a large number of different central nervous tissues (CNS) and peripheral nervous tissues (PNS), using conventional thin sections, thicker sections (100 nm or more) and 3-dimensional reconstructions of serial thin sections. Extensions were commonly observed, particularly from the ends of longitudinally oriented mitochondria in axons and dendrites. Often these had the appearance of, and could be traced into apparent continuity with, adjacent elements of the agranular membrane. In addition to these apical tubular extensions, we also observed and reconstructed short lateral tubular or sac-like extensions and vesicular protrusions of the outer mitochondrial membrane. We discuss and discount the possibility that the extensions are artefacts, consider the structural and biochemical similarities between the outer mitochondrial membrane and agranular reticulum and propose that the outer mitochondrial is part of the agranular reticulum (or a specialized portion of the agranular reticulum). We suggest that the translocation of mitochondria in nerve cells, and probably in other cells as well, involves movement of the inner mitochondrial membrane and the enclosed matrix (mitoplast) within channels of agranular reticulum in continuity, or in transient continuity, with the outer mitochondrial membrane.

scholarly journals Molecular mechanism of mitochondrial phosphatidate transfer by Ups1

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Jiuwei Lu ◽  
Chun Chan ◽  
Leiye Yu ◽  
Jun Fan ◽  
Fei Sun ◽  
...  
Keyword(s):  
Conformational Changes ◽  
Mitochondrial Membrane ◽  
Outer Mitochondrial Membrane ◽  
Mitochondrial Membranes ◽  
Inner Mitochondrial Membrane ◽  
Membrane Interaction ◽  
Detailed Mechanism ◽  
Physiological Regulator ◽  
Membrane Bound ◽  
Dynamics Simulations

AbstractCardiolipin, an essential mitochondrial physiological regulator, is synthesized from phosphatidic acid (PA) in the inner mitochondrial membrane (IMM). PA is synthesized in the endoplasmic reticulum and transferred to the IMM via the outer mitochondrial membrane (OMM) under mediation by the Ups1/Mdm35 protein family. Despite the availability of numerous crystal structures, the detailed mechanism underlying PA transfer between mitochondrial membranes remains unclear. Here, a model of Ups1/Mdm35-membrane interaction is established using combined crystallographic data, all-atom molecular dynamics simulations, extensive structural comparisons, and biophysical assays. The α2-loop, L2-loop, and α3 helix of Ups1 mediate membrane interactions. Moreover, non-complexed Ups1 on membranes is found to be a key transition state for PA transfer. The membrane-bound non-complexed Ups1/ membrane-bound Ups1 ratio, which can be regulated by environmental pH, is inversely correlated with the PA transfer activity of Ups1/Mdm35. These results demonstrate a new model of the fine conformational changes of Ups1/Mdm35 during PA transfer.

scholarly journals Molecular mechanism of mitochondrial phosphatidate transfer by Ups1/Mdm35

2019 ◽  
Author(s):  
Jiuwei Lu ◽  
Kevin Chan ◽  
Leiye Yu ◽  
Jun Fan ◽  
Yujia Zhai ◽  
...  
Keyword(s):  
Molecular Mechanism ◽  
Conformational Changes ◽  
Transfer Rate ◽  
Mitochondrial Membrane ◽  
Physiological Function ◽  
Bound State ◽  
Outer Mitochondrial Membrane ◽  
Structural Elements ◽  
Inner Mitochondrial Membrane ◽  
Dynamics Simulations

ABSTRACTCardiolipin plays many important roles for mitochondrial physiological function and is synthesized from phosphatidic acid (PA) at inner mitochondrial membrane (IMM). PA synthesized from endoplasmic reticulum needs to transfer to IMM via outer mitochondrial membrane (OMM). The transfer of PA between IMM and OMM is mediated by Ups1/Mdm35 protein family. Although there are many structures of this family available, the detailed molecular mechanism of how PA is transferred between membranes is yet unknown. Here, we report another crystal structures of Ups1/Mdm35 in the authentic monomeric apo state and the DHPA bound state. By combining subsequent all-atom molecular dynamics simulations, extensive structural comparisons and biophysical assays, we discovered the conformational changes of Ups1/Mdm35, identified key structural elements and residues during membrane binding and PA entry. We found the monomeric Ups1 on membrane is an important transit for the success of PA transfer, and the equilibrium between monomeric Ups1 and Ups1/Mdm35 complex on membrane affects the PA transfer rate and can be regulated by many factors including environmental pH.

scholarly journals Resolution and Reconstitution of a Mammalian Membrane

1969 ◽  
Vol 54 (1) ◽  
pp. 38-49 ◽  
Author(s):  
Efraim Racker
Keyword(s):  
Cytochrome C ◽  
Oxidative Phosphorylation ◽  
Succinate Dehydrogenase ◽  
Mitochondrial Membrane ◽  
Inner Mitochondrial Membrane ◽  
Submitochondrial Particles ◽  
Highly Sensitive ◽  
Cytochrome C1 ◽  
Coupling Factors ◽  
Oxidation Chain

The problem of the resolution and reconstitution of the inner mitochondrial membrane has been approached at three levels. (1) Starting with phosphorylating submitochondrial particles, a "resolution from without" can be achieved by stripping of surface components. The most extensive resolution was recently obtained with the aid of silicotungstate. Such particles require for oxidative phosphorylation the addition of several coupling factors as well as succinate dehydrogenase. (2) Starting with submitochondrial particles that have been degraded by trypsin and urea a resolution of the inner membrane proper containing an ATPase has been achieved. These experiments show that at least five components are required for the reconstitution of an oligomycin-sensitive ATPase: a particulate component, F1, Mg++, phospholipids, and Fc. Morphologically, the reconstituted ATPase preparations resemble submitochondrial particles. (3) Starting with intact mitochondria individual components of the oxidation chain have been separated from each other. The following components were required for the reconstitution of succinoxidase: succinate dehydrogenase, cytochrome b\, cytochrome c1, cytochrome c, cytochrome oxidase, phospholipids and Q10. The reconstituted complex had properties similar to those of phosphorylating submitochondrial particles; i.e., the oxidation of succinate by molecular oxygen was highly sensitive to antimycin.

scholarly journals Phosphatidylethanolamine made in the inner mitochondrial membrane is essential for yeast cytochromebc1complex function

2018 ◽  
Author(s):  
Elizabeth Calzada ◽  
J. Michael McCaffery ◽  
Steven M. Claypool
Keyword(s):  
Mitochondrial Function ◽  
Mitochondrial Membrane ◽  
Complex Iii ◽  
Biosynthetic Pathways ◽  
Outer Mitochondrial Membrane ◽  
Endomembrane System ◽  
Inner Mitochondrial Membrane ◽  
Mitochondrial Inner Membrane ◽  
Functional Analyses ◽  
Made In

ABSTRACTOf the four separate PE biosynthetic pathways in eukaryotes, one occurs in the mitochondrial inner membrane (IM) and is executed by phosphatidylserine decarboxylase (Psd1p). Deletion of Psd1, which is lethal in mice, compromises mitochondrial function. We hypothesize that this reflects inefficient import of non-mitochondrial PE into the IM. To test this, we re-wired PE metabolism in yeast by re-directing Psd1p to the outer mitochondrial membrane or the endomembrane system. Our biochemical and functional analyses identified the IMS as the greatest barrier for PE import and demonstrated that PE synthesis in the IM is critical for cytochromebc1complex (III) function. Importantly, mutations predicted to disrupt a conserved PE-binding site in the complex III subunit, Qcr7p, impaired complex III activity similar toPSD1deletion. Collectively, these data demonstrate that PE made in the IM by Psd1p is critical to support the intrinsic functionality of complex III and establish one likely mechanism.

Contribution of renal medullary mitochondrial density to urinary concentrating ability in mammals

1991 ◽  
Vol 261 (3) ◽  
pp. R719-R726 ◽  
Author(s):  
S. Abrahams ◽  
L. Greenwald ◽  
D. L. Stetson
Keyword(s):  
Metabolic Rate ◽  
Body Mass ◽  
Mitochondrial Membrane ◽  
Basolateral Membrane ◽  
Inner Mitochondrial Membrane ◽  
Membrane Area ◽  
Mitochondrial Density ◽  
Cellular Volume ◽  
Urinary Concentrating Ability ◽  
The Relationship

In mammals, the length of the loops of Henle increases with increasing body size without a concomitant rise in urinary concentrating ability. Because mass-specific metabolic rate falls with increasing body mass, this study sought to determine the extent to which this decline in metabolic rate could explain the low urinary concentrating ability of large mammals with long loops of Henle. Mitochondrial ultrastructural parameters were measured in the medullary thick ascending limbs (mTALs) of a series of nine mammalian genera ranging in body mass from 0.011 kg (bats) to approximately 400 kg (horses). The volume of mitochondria as a percent of mTAL cellular volume declined with increasing body mass (Mb-0.056). Inner mitochondrial membrane area per volume of mitochondrion also declined with increasing body mass (Mb-0.034), as did basolateral membrane area per unit mTAL cellular volume (Mb-0.075). Thus, not only do mitochondria occupy more volume of mTAL cells of smaller mammals, but those mitochondria are also more densely packed with cristae. Inner mitochondrial membrane area per unit volume of mTAL cell cytoplasm scaled as Mb-0.092. The decline in inner mitochondrial membrane area and basolateral membrane area per volume of mTAL cell may explain at least in part the relationship between body mass and renal concentrating ability in mammals of different sizes.

scholarly journals Tim50’s presequence receptor domain is essential for signal driven transport across the TIM23 complex

2011 ◽  
Vol 195 (4) ◽  
pp. 643-656 ◽  
Author(s):  
Christian Schulz ◽  
Oleksandr Lytovchenko ◽  
Jonathan Melin ◽  
Agnieszka Chacinska ◽  
Bernard Guiard ◽  
...  
Keyword(s):  
Binding Sites ◽  
Mitochondrial Membrane ◽  
Protein Import ◽  
Mitochondrial Protein ◽  
Mitochondrial Proteins ◽  
Outer Mitochondrial Membrane ◽  
Inner Mitochondrial Membrane ◽  
Mitochondrial Protein Import ◽  
Targeting Signals ◽  
Receptor Domain

N-terminal targeting signals (presequences) direct proteins across the TOM complex in the outer mitochondrial membrane and the TIM23 complex in the inner mitochondrial membrane. Presequences provide directionality to the transport process and regulate the transport machineries during translocation. However, surprisingly little is known about how presequence receptors interact with the signals and what role these interactions play during preprotein transport. Here, we identify signal-binding sites of presequence receptors through photo-affinity labeling. Using engineered presequence probes, photo cross-linking sites on mitochondrial proteins were mapped mass spectrometrically, thereby defining a presequence-binding domain of Tim50, a core subunit of the TIM23 complex that is essential for mitochondrial protein import. Our results establish Tim50 as the primary presequence receptor at the inner membrane and show that targeting signals and Tim50 regulate the Tim23 channel in an antagonistic manner.

scholarly journals Bax Is Present as a High Molecular Weight Oligomer/Complex in the Mitochondrial Membrane of Apoptotic Cells

2001 ◽  
Vol 276 (15) ◽  
pp. 11615-11623 ◽  
Author(s):  
Bruno Antonsson ◽  
Sylvie Montessuit ◽  
Belen Sanchez ◽  
Jean-Claude Martinou
Keyword(s):  
Molecular Weight ◽  
Membrane Protein ◽  
Hela Cells ◽  
Mitochondrial Membrane ◽  
Outer Mitochondrial Membrane ◽  
Inner Mitochondrial Membrane ◽  
Voltage Dependent Anion Channel ◽  
Large Molecular Weight ◽  
Mitochondrial Membrane Protein

Bax is a Bcl-2 family protein with proapoptotic activity, which has been shown to trigger cytochromecrelease from mitochondria bothin vitroandin vivo. In control HeLa cells, Bax is present in the cytosol and weakly associated with mitochondria as a monomer with an apparent molecular mass of 20,000 Da. After treatment of the HeLa cells with the apoptosis inducer staurosporine or UV irradiation, Bax associated with mitochondria is present as two large molecular weight oligomers/complexes of 96,000 and 260,000 Da, which are integrated into the mitochondrial membrane. Bcl-2 prevents Bax oligomerization and insertion into the mitochondrial membrane. The outer mitochondrial membrane protein voltage-dependent anion channel and the inner mitochondrial membrane protein adenosine nucleotide translocator do not coelute with the large molecular weight Bax oligomers/complexes on gel filtration. Bax oligomerization appears to be required for its proapoptotic activity, and the Bax oligomer/complex might constitute the structural entirety of the cytochromec-conducting channel in the outer mitochondrial membrane.

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