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Full-Text Articles in Life Sciences

Stomatin-Like Protein 2 Deficiency In T Cells Is Associated With Altered Mitochondrial Respiration And Defective Cd4+ T Cell Responses., Darah A Christie, Panagiotis Mitsopoulos, Julianna Blagih, Stanley D Dunn, Julie St-Pierre, Russell G Jones, Grant M Hatch, Joaquín Madrenas Sep 2013

Stomatin-Like Protein 2 Deficiency In T Cells Is Associated With Altered Mitochondrial Respiration And Defective Cd4+ T Cell Responses., Darah A Christie, Panagiotis Mitsopoulos, Julianna Blagih, Stanley D Dunn, Julie St-Pierre, Russell G Jones, Grant M Hatch, Joaquín Madrenas

Stanley D Dunn

Stomatin-like protein 2 (SLP-2) is a mostly mitochondrial protein that regulates mitochondrial biogenesis and function and modulates T cell activation. To determine the mechanism of action of SLP-2, we generated T cell-specific SLP-2-deficient mice. These mice had normal numbers of thymocytes and T cells in the periphery. However, conventional SLP-2-deficient T cells had a posttranscriptional defect in IL-2 production in response to TCR ligation, and this translated into reduced CD4(+) T cell responses. SLP-2 deficiency was associated with impaired cardiolipin compartmentalization in mitochondrial membranes, decreased levels of the NADH dehydrogenase (ubiquinone) iron-sulfur protein 3, NADH dehydrogenase (ubiquinone) 1β subcomplex subunit …


Characterization Of The Monomer-Dimer Equilibrium Of Recombinant Histo-Aspartic Protease From Plasmodium Falciparum, Huogen Xiao, Lee-Ann Briere, Stanley Dunn, Rickey Yada Oct 2012

Characterization Of The Monomer-Dimer Equilibrium Of Recombinant Histo-Aspartic Protease From Plasmodium Falciparum, Huogen Xiao, Lee-Ann Briere, Stanley Dunn, Rickey Yada

Stanley D Dunn

Histo-aspartic protease (HAP) from Plasmodium falciparum is an intriguing aspartic protease due to its unique structure. Our previous study reported the first recombinant expression of soluble HAP, in its truncated form (lys77p-Leu328) (p denotes prosegment), as a thioredoxin (Trx) fusion protein Trx-tHAP. The present study found that the recombinant Trx-tHAP fusion protein aggregated during purification which could be prevented through the addition of 0.2% CHAPS. Trx-tHAP fusion protein was processed into a mature form of tHAP (mtHAP) by both autoactivation, and activation with either enterokinase or plasmepsin II. Using gel filtration chromatography as well as sedimentation velocity and equilibrium ultracentrifugation, …


The B Subunits In The Peripheral Stalk Of F1f0 Atp Synthase Preferentially Adopt An Offset Relationship, Shane Claggett, Mac O'Neil Plancher, Stanley Dunn, Brian Cain Oct 2012

The B Subunits In The Peripheral Stalk Of F1f0 Atp Synthase Preferentially Adopt An Offset Relationship, Shane Claggett, Mac O'Neil Plancher, Stanley Dunn, Brian Cain

Stanley D Dunn

The peripheral stalk of F1F0 ATP synthase is essential for the binding of F1 to FO and for proper transfer of energy between the two sectors of the enzyme. The peripheral stalk of Escherichia coli is composed of a dimer of identical b subunits. In contrast, photosynthetic organisms express two b-like genes that form a heterodimeric peripheral stalk. Previously we generated chimeric peripheral stalks in which a portion of the tether and dimerization domains of the E. coli b subunits were replaced with homologous sequences from the b and b' subunits of Thermosynechococcus elongatus (Claggett, S. B., Grabar, T. B., …


Functionally Compensating Coevolving Positions Are Neither Homoplasic Nor Conserved In Clades, Gregory Gloor, Gaurav Tyagi, Dana Abrassart, Andrew Kingston, Andrew Fernandes, Stanley Dunn, Christopher Brandl Oct 2012

Functionally Compensating Coevolving Positions Are Neither Homoplasic Nor Conserved In Clades, Gregory Gloor, Gaurav Tyagi, Dana Abrassart, Andrew Kingston, Andrew Fernandes, Stanley Dunn, Christopher Brandl

Stanley D Dunn

We demonstrated that a pair of positions in phosphoglycerate kinase that score highly by three nonparametric covariation measures are important for function even though the positions can be occupied by aliphatic, aromatic, or charged residues. Examination of these pairs suggested that the majority of the covariation scores could be explained by within-clade conservation. However, an analysis of diversity showed that the conservation within clades of covarying pairs was indistinguishable from pairs of positions that do not covary, thus ruling out both clade conservation and extensive homoplasy as means to identify covarying positions. Mutagenesis showed that the residues in the covarying …


36 Degrees Step Size Of Proton-Driven C-Ring Rotation In Fof1-Atp Synthase, Monika Düser, Nawid Zarrabi, Daniel Cipriano, Stefan Ernst, Gary Glick, Stanley Dunn, Michael Börsch Oct 2012

36 Degrees Step Size Of Proton-Driven C-Ring Rotation In Fof1-Atp Synthase, Monika Düser, Nawid Zarrabi, Daniel Cipriano, Stefan Ernst, Gary Glick, Stanley Dunn, Michael Börsch

Stanley D Dunn

Synthesis of adenosine triphosphate ATP, the 'biological energy currency', is accomplished by F(o)F(1)-ATP synthase. In the plasma membrane of Escherichia coli, proton-driven rotation of a ring of 10 c subunits in the F(o) motor powers catalysis in the F(1) motor. Although F(1) uses 120 degrees stepping during ATP synthesis, models of F(o) predict either an incremental rotation of c subunits in 36 degrees steps or larger step sizes comprising several fast substeps. Using single-molecule fluorescence resonance energy transfer, we provide the first experimental determination of a 36 degrees sequential stepping mode of the c-ring during ATP synthesis.