scholarly journals Interaction of mitochondrial malate dehydrogenase monomer with phospholipid vesicles

1979 ◽  
Vol 178 (1) ◽  
pp. 147-158 ◽  
Author(s):  
K A Webster ◽  
H V Patel ◽  
K B Freeman ◽  
D Papahadjopoulos
Keyword(s):  
Conformational Change ◽  
Malate Dehydrogenase ◽  
Alpha Helix ◽  
Phospholipid Vesicles ◽  
Mitochondrial Matrix ◽  
Enzyme Subunits ◽  
Direct Binding ◽  
Mitochondrial Malate Dehydrogenase ◽  
Circular Dichroïsm ◽  
In Cells

The association between bovine and porcine mitochondrial malate dehydrogenase (EC 1.1.1.37) and phospholipid vesicles was investigated. At concentrations at which malate dehydrogenase exists as a dimer, entrapment within the aqueous compartment but not binding of the 14C-labelled enzyme was observed. The dissociated enzyme was labile to moderate heat and to p-chloromercuribenzoate, but in both cases inactivation was decreased by incubation with suspensions of charged phospholipid vesicles. This suggested an interaction between enzyme subunits and phospholipid, and this was confirmed by direct binding measurements and by studies that followed changes in the fluorescein-labelled enzyme. The circular-dichroism spectra of the enzyme indicated a high alpha-helix content, and suggested that a small conformational change occurred when the enzyme dissociated. Fluorescence data also suggested less-rigid molecules after dissociation. A possible mechanism, based on the flexibility of enzyme monomer and its interaction with phospholipids, by which mitochondrial matrix enzymes are specifically localized in cells, is discussed.

scholarly journals Hydrophobic interaction between the monomer of mitochondrial malate dehydrogenase and phospholipid membranes

1980 ◽  
Vol 186 (1) ◽  
pp. 227-233 ◽  
Author(s):  
K A Webster ◽  
K B Freeman ◽  
S Ohki
Keyword(s):  
Malate Dehydrogenase ◽  
Conformational Changes ◽  
Ribonuclease A ◽  
Phospholipid Vesicles ◽  
Mitochondrial Matrix ◽  
Dimer Formation ◽  
Dimeric Form ◽  
Oil Water ◽  
Mitochondrial Malate Dehydrogenase

Porcine mitochondrial malate dehydrogenase (EC 1.1.1.37) dissociates into subunits on dilution. The enzyme monomer caused large increases in the surface pressure of monolayers of 1:1 phosphatidylserine/phosphatidylcholine at air/water and oil/water interfaces. The monomer increased the permeability of phospholipid vesicles to 22Na+. Both effects were significantly greater than the corresponding effects of ribonuclease A, cytochrome c and the dimeric form of malate dehydrogenase. Changes in the circular-dichroism spectra of the enzyme indicated that conformational changes may be associated with dimer formation or when monomer interacts with lysophosphatidyl-choline. Similar interactions to those described may occur in situ when mitochondrial malate dehydrogenase is transported to the mitochondrial matrix from its site of synthesis on cytosolic ribosomes.

Translocation of precursor proteins into the mitochondrial matrix occurs through an environment accessible to aqueous perturbants

1989 ◽  
Vol 94 (4) ◽  
pp. 695-701 ◽  
Author(s):  
E.S. Sztul ◽  
T.W. Chu ◽  
A.W. Strauss ◽  
L.E. Rosenberg
Keyword(s):  
Malate Dehydrogenase ◽  
Integral Membrane Proteins ◽  
Leader Peptide ◽  
Mitochondrial Matrix ◽  
Mitochondrial Membranes ◽  
Precursor Proteins ◽  
Nonionic Detergent ◽  
Triton X ◽  
Polypeptide Chains ◽  
Mitochondrial Malate Dehydrogenase

We have identified translocational intermediates generated during import of precursor proteins into the mitochondrial matrix and have characterized their association with mitochondrial membranes. Partially translocated forms of mitochondrial malate dehydrogenase (MDH) and ornithine transcarbamylase (OTC) were generated during import of the corresponding precursors (pMDH and pOTC) into mitochondria at 2 degrees C. Import at this temperature results in the formation of intermediate-sized MDH (iMDH) and OTC (iOTC) produced by the removal of a portion of the leader peptide, and in the production of mature-sized MDH. All of these forms contain NH2 termini located within the mitochondrial matrix, although the majority of their polypeptide chains remain extramitochondrial. All three are strongly associated with mitochondrial membranes, but can be extracted by protein denaturants such as urea. These translocational intermediates appear to be hydrophilic proteins, on the basis of their partitioning properties during extraction with the nonionic detergent Triton X-114. The data indicate that the translocation of polypeptide chains into mitochondria occurs in a microenvironment that is aqueous in nature and is mediated by integral membrane proteins.

scholarly journals Parallel G-quadruplexes recruit the HSV-1 transcription factor ICP4 to promote viral transcription in herpes virus-infected human cells

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Ilaria Frasson ◽  
Paola Soldà ◽  
Matteo Nadai ◽  
Sara Lago ◽  
Sara N. Richter
Keyword(s):  
Transcription Factor ◽  
Early Gene ◽  
Proximity Ligation Assay ◽  
Gene Promoters ◽  
Herpes Simplex Virus 1 ◽  
Direct Binding ◽  
Simplex Virus ◽  
In Cells ◽  
Hsv 1

AbstractG-quadruplexes (G4s) are four-stranded nucleic acid structures abundant at gene promoters. They can adopt several distinctive conformations. G4s have been shown to form in the herpes simplex virus-1 (HSV-1) genome during its viral cycle. Here by cross-linking/pull-down assay we identified ICP4, the major HSV-1 transcription factor, as the protein that most efficiently interacts with viral G4s during infection. ICP4 specific and direct binding and unfolding of parallel G4s, including those present in HSV-1 immediate early gene promoters, induced transcription in vitro and in infected cells. This mechanism was also exploited by ICP4 to promote its own transcription. Proximity ligation assay allowed visualization of G4-protein interaction at the single selected G4 in cells. G4 ligands inhibited ICP4 binding to G4s. Our results indicate the existence of a well-defined G4-viral protein network that regulates the productive HSV-1 cycle. They also point to G4s as elements that recruit transcription factors to activate transcription in cells.

Comparison of the precursor and mature forms of rat heart mitochondrial malate dehydrogenase

Biochemistry ◽  
1987 ◽  
Vol 26 (1) ◽  
pp. 128-134 ◽  
Author(s):  
Paula M. Grant ◽  
Steven L. Roderick ◽  
Gregory A. Grant ◽  
Leonard J. Banaszak ◽  
Arnold W. Strauss
Keyword(s):  
Malate Dehydrogenase ◽  
Rat Heart ◽  
Mitochondrial Malate Dehydrogenase
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